“Thou shalt not commit adultery.” (Exodus 20:14)
“Nor come nigh to fornication/adultery: for it is a shameful (deed) and an evil, opening the road (to other evils).” (Sura 17:32)
Frustration with moral relativism and subjectivism motivates some thinkers to look to religion for objective and universally binding moral judgments. If we can ground morality in God, then morality will be objective, and we can determine with confidence our moral rights and obligations. Moreover, an answer to the question of why one ought to live morally will be near at hand. This chapter will examine two forms of religious morality—the Divine Command and Natural Law theories of morality. We will see that both theories run into serious challenges. In the final section, we will consider how religious belief and practice might nevertheless support living a moral life.
For the most part, this chapter concerns itself with the Abrahamic religions (Judaism, Christianity and Islam, which all have their origins in the prophet Abraham). Box A briefly discusses religion in non-monotheistic faiths. The Abrahamic faiths conceive of God as personal, omniscient and omnipotent. God is the creator of the universe, which depends on God for its continued existence. These faiths also deem God to have given commands, such as the command not to commit adultery. The total set of these commands is the moral code of the religion. Many people initially learn morality within religious contexts: in churches, mosques, synagogues and temples, as well as in families inspired by teachings from these institutions. Often, people defer to religious authorities or traditions regarding significant moral quandaries, both in their own lives and in their societies, including abortion, capital punishment, or vegetarianism. Even in liberal societies, people often consult religious authorities on controversial practical matters. Given that religious thinkers are often professionally concerned with ethical matters, consulting them does not seem entirely misplaced. However, even if we acknowledge that religion is connected to morality, there are important issues that demand philosophical clarification.
We begin with a discussion of the Divine Command Theory of Morality (DCT), which is a metaethical theory—a theory about the nature of ethical reasoning—that sees moral obligation as equivalent to, and dependent on, the commands of God. We will see that, despite some merits, the DCT is open to serious and persuasive challenges. We will then move onto a discussion of another form of religious ethics, the Natural Law Theory of Morality (NLT). Again, while recognizing some merits of this way of thinking of morality, we will see that it too has some serious weaknesses. Finally, we will consider some ways in which religious faith might support moral life, even if morality is not dependent on faith.
The Abrahamic religions (Judaism, Christianity and Islam) agree that God is personal and issues commands to which we ought to conform. Not all religions accept this way of thinking; some are polytheistic, holding that there exists a plurality of gods; others do not think of the ultimate reality as personal at all. Hinduism is notoriously difficult to pin down, but some forms, such as Advaita Vedanta, think of ultimate reality as non-personal, although others, including Ramanuja’s Vishishtadvaita, hold to a conception of God very similar to the Abrahamic religions. Some forms of Buddhism accept the existence of gods, but Buddhism does not accept the existence of a permanent and independent god that is the source and sustainer of the universe. Daoist religions accept the existence of the Dao, which transcends personal experience, but is understood quasi-naturalistically, as a fundamental order in the universe. The variations in the non-monotheistic religions mean that it would be folly to generalize about ethics within these faiths. That said, it is clear that, lacking a personal god, the Divine Command Theory cannot apply to these religions. Furthermore, Thomas Aquinas’s version of the Natural Law Theory also cannot apply, for it depends on the designed creation of the world by a personal god. Nevertheless, Daoism, Buddhism, and some forms of Hinduism, as well as some North American Indigenous religions, might be thought of as reflecting versions of Natural Law Ethics, inasmuch as they rest on alleged natural facts about the world.
The Divine Command Theory of Morality
The Divine Command Theory of Morality (DCT) is a relatively simple theory of moral obligation that equates our moral duties to the commandments of God:
- X is morally obligatory if and only if God has commanded X.
- Y is morally prohibited if and only if God has forbidden Y.
Moreover, the DCT holds that God’s commands are the source of morality. Consider, for example, the seventh commandment, “thou shall not commit adultery.” Assuming that God exists and has indeed issued this command, then, according to the DCT, it is morally wrong to commit adultery. If God does not exist or has not issued the command, then adultery is morally permissible.
The motivation behind this theory is obvious: with its universal rules, the DCT at once solves challenges of relativism and of why one ought to be moral (some argue that the idea of an objective morality only makes sense if a personal god exists—see Box B). Furthermore, the DCT emphasizes the idea that moral commands are overriding, in the sense that they trump other motivations such as convenience or self-interest. Other theories seem deficient in these respects. For example, one might attempt to support a rule prohibiting adultery on consequentialist grounds (see Chapter 5), pointing out the likelihood that adultery leads to suffering. However, such reasons will be open to exceptions—what about situations in which suffering does not ensue? Perhaps one could reject adultery on deontological grounds (see Chapter 6), using Kantian reasons about the violation of vows and the lying that typically occurs in adultery, but these considerations might allow adultery in the case of open marriages. Another possibility is that we reject adultery on cultural grounds, seeing it as not what “we” do. The DCT, however, makes it clear that if God prohibits adultery, then it is absolutely wrong whether or not it leads to suffering, violates a cultural norm, or violates the categorical imperative. Furthermore, the DCT suggests a strong reason to act morally: morality is essentially submission to the authority of the creator, who may punish transgressors.
The DCT tries to equate morality to the purported commands of God. Some thinkers, for instance Robert Adams (1999), argue that the existence of objective moral obligations is coherent only if a personal God exists. In other words, the idea is that objective morality either presupposes that God exists, or that the existence of God is the best explanation of objective moral obligations. Consideration of such arguments, some which can be traced to Immanuel Kant (1788), would take us too far from the central themes of this chapter. However, see Evans (2018) for a more detailed discussion of these arguments.
The DCT is interesting in that, in contrast with most other theories of ethical action, it emphasizes obedience or submission as a central virtue—not obedience in general, of course, but to God and perhaps to God’s representatives. The idea of moral autonomy, of determining the right course of action using one’s reason, is not emphasized. One does need to use reason, perhaps to determine whether an action falls under the scope of a particular commandment, but the principal virtue for the DCT is obedience to the will of God. This may for some people be attractive as it offers an escape from the weighty demands of moral judgment; one essentially transfers responsibility to a third party. One major religion reflects this idea in its very name: in Arabic, “Islam” means submission, and a “Muslim” is one who submits (to Allah).
Some theists (people who believe that God exists) might think of the DCT as consistent with their overall worldview. It may seem that if God has created the world and everything that exists, then God must have created morality too. Furthermore, if God is omnipotent, then it would seem that God could choose any morality—we are just fortunate that God chose a morality that facilitates human flourishing. However, as we dig a little deeper, some serious problems appear.
Some problems arise from the application of the theory to practical decision making. How do we know what God has commanded? One of the virtues of the DCT is supposed to be its moral clarity, but the DCT is not so unequivocal as it appears. First, the DCT presupposes that we have the right religion, and also that we interpret that religion correctly. Clearly, this is going to make it very challenging to apply the DCT to issues that demand agreement with those of diverse or no faith. Second, how can we resolve issues that arise from applying ancient commands to contemporary moral problems, including problems arising from human cloning, pornography, assisted suicide, or nuclear weapons? Minimally, we will need to use our judgment to determine what the commands suggest God would have commanded, but this will render obedience less clear. Third, to make matters worse, God has issued multiple commands, sometimes leading to dilemmas in which we are commanded to do two incompatible actions. What if the only way to “honor thy parents” is to “bear false witness,” or if keeping the Sabbath holy will require violating the duty to honor thy parents? Supporters of the DCT can develop responses to these problems of application, but the cost will be that the theory will lose its simplicity, one of its chief attractions. However, even if we put these challenges aside and agree that we know that God has, for example, forbidden adultery, there remains a still more fundamental challenge to the DCT.
The challenge is sometimes called the “Euthyphro dilemma,” as it is expressed in Plato’s Dialogue Euthyphro (see Box C). To understand the challenge, suppose that God exists and has forbidden adultery. Then, adultery is immoral, according to the DCT. However, is adultery immoral because God forbids it? Or does God forbid adultery because it is immoral? Whatever our response, puzzles arise.
Plato’s Euthyphro is written from the context of polytheistic religion, and is concerned with the idea of piety or holiness, which may not be precisely the same as the idea of moral rightness or moral good. In a dialogue with Euthyphro, the participants inquire into the nature of piety. When Euthyphro suggests that piety is that of which the gods approve, Socrates (after reflection on the issue of disagreements between the various gods) asks whether X is pious because the gods approve of X, or whether the gods approve of X because X is pious. The question is a gem in philosophy: Socrates is expressing a puzzle that is often called a dilemma because neither option is satisfactory for the believer.
On the one hand, if God forbids adultery because it is immoral, then God has reasons for the command. We could suppose that God is broadly consequentialist and forbids adultery because of the bad consequences to which it leads. Or perhaps God forbids adultery because it violates a promise typically made in marriage vows, a consideration that we could cast in broadly Kantian terms. Either way, if God appeals to either consequentialist or Kantian principles, it follows that theoretically at least, humans could determine that adultery is immoral without knowledge of God’s commands. This response to the Euthyphro dilemma implies that the source of morality is not God’s commands; while these commands may be helpful, they are logically redundant: our moral duties are equivalent to the commands of God, but they are not based on God’s commands. Consequently, taking this stance on the Euthyphro dilemma implies that morality is logically independent of God.
Note that this response denies neither that God forbids adultery, nor that adultery is immoral. It rather holds that there is a deeper reason for the command forbidding adultery. If God applies perfect reason to determine which actions are forbidden or required, then the principles on which God relies are the ultimate source of moral obligation.
Still, we might acknowledge that human reason is often imperfect, short-sighted or overly self-interested. The consequences of our actions are often unforeseeable, but God’s omniscience permits more accurate, if not perfect, predictions of the consequences of our actions. So, while in one sense redundant, God’s commands ought not to be ignored; they are based on superior reason and knowledge, and thus can be a more reliable source of moral knowledge than our own reason—indeed, this is known as God’s providence. However, to respond to the Euthyphro dilemma by affirming that God forbids adultery because it is immoral effectively rejects the DCT. It would mean that God’s commandments are based on morality. However, from the DCT’s standpoint, this cannot be true.
On the other hand, suppose we affirm that adultery is immoral because God forbids it. Then, from our human point of view, it is objectively wrong to commit adultery, but from God’s point of view, there is no moral reason to forbid adultery. If God has a reason for forbidding adultery, then we are implying the existence of another source of morality, thus bringing us back to the independence option. However, if adultery is wrong because God forbids it, then we must accept that God’s commandments are arbitrary. God does forbid adultery, we might say, but God might as well have allowed it on special days—say, on one’s birthday or on blue moons. As bizarre as these options seem, they are candidates from God’s perspective. The fact that we consider these options “bizarre” is a sign that we presuppose that there are reasons for rejecting adultery that have nothing to do with God’s commands.
So, the options seem to be that either God has reasons for issuing commands or God does not. If God does have reasons, then we seem to be forced to admit some deeper principles on which God’s commands are based. This is the independence option. If God does not have reasons for the commands, then the commands are arbitrary. Neither alternative is attractive, thus giving us reason to reject the DCT. However, some thinkers, including Christian philosopher William Lane Craig, argue that the Euthyphro presents a false dilemma, which is the fallacy of assuming that there are just two options when in fact there are multiple options.
Craig argues that God is essentially good, meaning that goodness is part of God’s nature:
There’s a third alternative, namely, God wills something because He is good. What do I mean by that? I mean that God’s own nature is the standard of goodness, and His commandments to us are expressions of His nature. In short, our duties are determined by the commands of a just and loving God. (Craig 2010, 135-6)
Craig is arguing that moral rules are neither independent of God, nor are they arbitrary. The command not to commit adultery is based on God’s own goodness; it is therefore not arbitrary. Nor is the command independent of God, as it is only through the good nature of God that the command occurs in the first place.
In response, we can note that the claim that God is the “standard of goodness” does not really escape the problem. Consider Craig’s assertion that God is “just and loving.” If one says this about another person, then the claim is meaningful; this person satisfies the independent standards of being loving and just. However, if “God’s own nature is the standard of goodness,” then saying that God is “just and loving” means that whatever God does would be equally just and loving. This seems to be the arbitrariness option, albeit in disguised form. So, it is unclear how Craig’s idea presents a third option.
A stronger and more subtle response to the Euthyphro dilemma comes from the work of Robert Adams (1979), who has proposed a less extreme version of the DCT, which he calls the Modified Divine Command Theory (MDCT). Recall, the DCT holds that to say X is morally wrong is to say that God has forbidden X. This is usually understood as implying that God’s commands are the source of our moral obligations. Indeed, that is how we have been considering the theory so far. However, Adams understands the DCT as articulating the equivalence between our moral obligations and the commands of a loving God. Thus, to say that one must not commit adultery is to say that a loving God commands us not to commit adultery. Adams’ MDCT does not insist that God’s commands are the source of moral obligation. Indeed, Adams’ position begins from a stance of confidence in basic moral facts, such as the wrongness of causing unnecessary suffering, arguing that the existence of a loving, intelligent God is the best explanation for those objective moral facts.
Adams’ MDCT is an example of how philosophical theories respond to criticism, such as the Euthyphro dilemma. Adams accepts that the arbitrariness of God is not tolerable, but does not give up the DCT entirely. Rather, he reimagines the theory as insisting on the identity of moral rules with God’s commands, but gives up the idea that the source of morality lies in the arbitrary commands of God. The strategy is promising but we should note that Adams has given up the idea that adultery, for example, is wrong because God forbids it.
The Natural Law Theory of Morality
The DCT is still embraced by some theistic thinkers today, often in a modified form such as Craig’s or Adams’. However, many theists argue for a different conception of the relationship between God and morality. One important theistic moral tradition is the Natural Law Theory of Morality (NLT). This approach to morality does not deny that God issues commands, but instead takes morality to be implicit in God’s creation of the universe and rational human beings. The idea is that the universe is created by God with everything holding a natural purpose. These purposes can be determined by careful study, using our reason. From knowledge of the proper purposes of objects, one can identify the proper ways to interact with the world and each other.
The moral theology of Thomas Aquinas (1225-1274 CE) contains one influential version of the NLT. Aquinas derives his underlying metaphysics from Aristotle (384-322 BCE). For Aristotle, understanding any object requires knowing four aspects of it. We must know of what it is made (its material cause), its form (formal cause), how it came to be (its efficient cause), and its function (its final cause). Consider rain, for example. The material cause of rain is water; its formal cause is droplets of liquid falling from clouds; and its efficient cause is the condensation of vapor along with the force of gravity. Its final cause can be thought of as its functions of watering plants and refilling the streams and lakes from which we drink. As it turns out, science today has progressed greatly by rejecting final causes, but for centuries western science was influenced by the Aristotelian idea that in order to understand X we need to know what X is for. In Aristotelian terms, the function of an object will be understood as how it fulfills functions within the system to which it belongs—teeth allow us to chew food, the heart functions as a pump to circulate the blood. The NLT easily bends the idea of an object’s function into its purpose, which further suggests how it ought to be used. Briefly, there are three components of this approach to morality:
- God created the universe, including human beings and other objects, with purposes.
- The purpose of objects in the world can be discerned using natural reason, with which God has endowed human beings.
- The purpose for which God created an object determines its proper use.
The upshot is that our capacity to discern God’s purposes in creation provides us with awareness of our ethical obligations. One of the strengths of the NLT is that it allows us to perceive God’s purposes without knowing God’s commands, or even believing that God exists.
For example, our reason allows us to identify that our sexual organs have the function of reproduction of our species. Indeed, for Aquinas, something can have just one final cause. So, reproduction is why God provided our sexual organs to us. If sexual organs are created solely in order to fulfill reproductive needs, then it would be wrong to use them for other purposes. In general, sex for pleasure becomes problematic, but especially so when reproduction is either impossible or thwarted; thus, homosexual acts, mechanical or chemical birth control, and masturbation are all ruled out on this account. These acts constitute use of sexual organs in ways that could not lead to reproduction. If we add the insight that marriage functions to provide a legitimate outlet for sexual needs and as a space for rearing children, then it will be clear that adulterous sex will also be wrong.
Aquinas’s version of the NLT is clearly theistic, as it presupposes the existence of an intelligent designer of the universe who has endowed us with the capacity to discern the natural law. However, it does not suggest that acts are right or wrong according to God’s arbitrary commands. Instead, it takes the position that when God commands us to do X, it is because X is right. Further, we do not need to believe in God in order to know what is right or wrong. Anyone, theist or not, is able to identify the laws of nature that govern morality, because these are implicit in nature itself. Why then would God give us commandments?
One reason is that God is able to infallibly identify the consequences of our actions. Human beings can predict the consequences of our actions (“if I shoot the gun at the man, then he will probably be killed”), but God’s omniscience implies infallible prediction. God even will be able to anticipate the consequences of our actions into the afterlife. Also, while God’s reasoning is impeccable, our own reasoning is subject to error, so we can use God’s commands as a failsafe that reliably allows us to determine the right course of action. So, if God has commanded us to do X, then under the NLT we should do X.
Still, the NLT is problematic. First, it presupposes a model of explanation at odds with today’s successful scientific reasoning. Science can proceed without identifying purposes in nature. Indeed, the onset of the scientific revolution is dependent on rejecting insistence on Aristotelian final causes. It is true that there are examples of functionalist reasoning in some areas of the life and human sciences—as when we say that the heart serves as a pump, but there is a significant difference between an object’s function and its purpose. The latter idea presupposes an intelligence that creates or guides the object in question. Second, the idea of an object’s function is not as clear as the theory suggests. Even if we allow that sex is for reproduction, it does not follow that it is only for reproduction, or that it could not be used for other purposes. Sex could be used to enhance intimacy, or perhaps just as a form of amusement, even if we allow that it also has the function of reproduction. Some proponents of the NLT will respond to this line of thinking in interesting ways, developing, for example, a doctrine of double effect (see Box D).
The Doctrine of Double Effect was originally proposed by Aquinas in Summa Theologica (II-II, Qu. 64, Art.7) in his defense of killing another person in self-defence. The basic idea is that it is okay to kill an attacker in self-defence, providing that one does not intend to kill—the killing must be a side-effect of one’s action, not its intention. This doctrine is often applied in cases of end-of-life care, where perhaps one acts in order to alleviate pain in a patient, but the action has the foreseeable, albeit unintended, consequence of causing the death of the patient. See McIntyre (2014) for a discussion of this doctrine.
A third and decisive challenge to the NLT is that it commits the naturalistic fallacy. British philosopher G. E. Moore (1873-1958), who introduced the term, argues that it is fallacious to infer claims about what is good or right (moral properties) from claims about natural properties (Moore  2004). Moore specifically offered the inference from something being pleasurable to it being good as an example. Earlier, David Hume (1711-1776) argued that claims about what ought to occur cannot be inferred from claims that describe the world; we cannot infer an “ought” claim from purely “is” claims (Hume  2009). The important differences between Hume’s and Moore’s positions need not detain us too much here; what we need to note is that the NLT would have us describe the world in purely naturalistic terms, then infer something about how the world ought to be. We observe, for example, that sex has an essential role in reproduction, then infer something about the proper role of sex. If either Hume or Moore are correct, such inferences are illegitimate, because the conclusions of our inferences include concepts that are not implicit in the premises. The challenge, in Moore’s terms, is that the NLT implies that goodness or rightness are natural properties, whereas in fact they are properties of an altogether different type.
So far, we have been considering the relation between God and the content of our moral obligations, the actual rules governing what actions we ought to perform. However, even if we conclude that our moral duties are independent of religious belief, we could still insist that religious faith contributes to living a moral life. In other words, religious practice might support our moral life in ways that are independent of determining how we ought to act.
An obvious point is that fear of divine punishment provides a powerful motivation for doing the right thing. Clearly, if the only reason one does not succumb to the temptation to murder is one’s fear of hell, then we can be glad that one has those religious beliefs! However, it seems that morality requires doing the right thing for the right reason, so we might want to insist that such action is not truly moral action.
More interestingly, faith and religion are more complex than simple adherence to a set of doctrines. Usually, religions are social institutions that have long histories that include stories of moral heroes (saints, prophets, etc.) contributing to our moral understanding. Furthermore, religions usually provide moral codes that enjoin us to proceed beyond the customary demands of the morality of the times, as when the Qur’an advises us to seek knowledge (Sura 20:114) or appreciate diversity (Sura 49:13). The Buddha advises us to develop compassion, and Christ demands that we love our neighbour; Guru Nanak insists on women’s equality from the beginnings of the Sikh faith. Even if adherents often fall short of these ideals, the ideas encourage us to move beyond what has been typically expected of people—in some cases, helping us to reconceive our moral relationships to those who have traditionally been left out of our moral thinking.
We should also recognize that as social institutions, religions provide support for others, both within and without the religion. Religions offer charities that support poverty alleviation, such as World Vision or the Aga Khan Foundation. These same charities offer opportunities for the adherent to make a moral difference in the world. Such voluntary work permits the individual to develop moral sensitivity and even courage. It will often allow the adherent to escape from the self-centeredness that so epitomizes much contemporary life. Indeed, the great twentieth-century philosopher of religion John Hick (2005) thinks of religions as mainly concerned with providing means by which we move beyond self-centeredness.
Another interesting idea to consider is what Robert Adams (1979) calls the problem of “demoralization” without religion. Adams, drawing on some enigmatic ideas from Kant’s Religion Within the Limits of Reason Alone ( 1960), suggests that the moral agent needs to have a sense that her moral actions will be effective—“contribute to a good world-history”—but this presupposes “a moral order of the universe.” Such an order, he argues is best, but not exclusively, offered by a theistic religious belief.
The idea is that the world presented to us by contemporary scientific understanding is a morally indifferent world, in which the agent has no guarantee that things will work out in the end, that one’s moral efforts are not in vain. Such a world is demoralizing inasmuch as it leads to questions about the point of moral life. The world presented to us by most theistic religions is one in which moral life will, ultimately at least, lead to a better world, for oneself as well as others. As such, religions make the sacrifices, demands and frustrations of moral life more attractive.
In response, we can agree with Adams that religion might make moral life more attractive for some people but insist that his argument does not support the stronger position that living morally demands religious faith. Quite clearly, there are millions of people who live moral lives without the assurance of a moral order in the universe brought about by religion.
Adams, Robert Merrihew. 1979. “Moral Arguments for Theistic Belief.” In Rationality and Religious Belief, ed. C. F. Delaney. Notre Dame, IN: University of Notre Dame Press.
Adams, Robert Merrihew. 1999. Finite and Infinite Goods. New York: Oxford University. Press.
Aquinas, Thomas. 1981. Summa Theologica. Trans. Fathers of the English Dominican Province. Westminster, MD: Christian Classics.
Craig, William Lane. 2010. On Guard: Defending Your Faith with Reason and Precision. Colorado Springs, CO: David C. Cook.
de Botton, Alain. 2012. Religion for Atheists: A Non-Believer’s Guide to the Uses of Religion. Toronto, ON: McClelland and Stewart.
Evans, C. Stephen. 2018. “Moral Arguments for the Existence of God.” In The Stanford Encyclopedia of Philosophy, ed. Edward N. Zalta. https://plato.stanford.edu/archives/fall2018/entries/moral-arguments-god
Hick, John. 2005. An Interpretation of Religion. 2nd revised ed. New Haven: Yale University Press.
Hume, David. (1739) 2009. A Treatise of Human Nature. Auckland, NZ: Floating Press.
Kant, Immanuel. (1785) 2002. Groundwork for the Metaphysics of Morals, ed. and trans. Allen W. Wood. New Haven: Yale University Press.
Kant, Immanuel. (1788) 1956. Critique of Practical Reason, trans. Lewis White Beck. Indianapolis, Indiana: Bobbs-Merrill.
Kant, Immanuel. (1793) 1960. Religion Within the Limits of Reason Alone. New York: Harper and Row.
McIntyre, Alison. 2014. “Doctrine of Double Effect.” In The Stanford Encyclopedia of Philosophy, ed. Edward N. Zalta. https://plato.stanford.edu/archives/win2014/entries/double-effect
Moore, George Edward. (1903) 2004. Principia Ethica. Mineola, NY: Dover Publications.
Plato. (ca. 390-380 BCE) 2018. Euthyphro, trans. Benjamin Jowett. https://www.gutenberg.org/ebooks/1642
- Note that the Qur’anic version of the rule against adultery (above) suggests that God forbids adultery for reasons. ↵
- “Cluelessness” is a well-known problem for consequentialist theories in general. See Greaves, Hilary. 2016. “Cluelessness.” Proceedings of the Aristotelian Society 116(3): 311-339. ↵
- There is an interesting problem of whether God has absolute knowledge of the future, if it is true that humans have free will. Theists clash on this issue. ↵
- See Kant (1785) 2002, Groundwork for the Metaphysics of Morals for a defense of this idea (also discussed in Chapter 6). ↵