Does God have obligations to us? No, He doesn’t. But doesn’t that imply that He could do anything to us? No, it doesn’t. But how can that be? To understand how, consider first another, related false dilemma: the famous Euthyphro problem.

The Euthyphro dilemma unfolds as follows: God commands us to do what is good. But is something good simply because God commands it, or does He command it because it is inherently good? If we consider the first option, it appears we may be accepting the possibility that God could render it good for us to torture babies merely for pleasure, solely through His command. If we adopt the second option, it suggests we are acknowledging a standard of goodness that exists independently of God, which He consults when issuing His commands. Neither option seems acceptable from the perspective of theism. The first renders morality arbitrary, making the assertion that God is good entirely trivial. The second contradicts the fundamental theistic belief that God is the ultimate cause of all things and, specifically, the source of all goodness. Therefore, we face a dilemma, don't we?

Actually, we don’t because the dilemma is a false one – certainly from the Thomistic perspective, for reasons I explain in Aquinas. Like all the other supposedly significant objections to theism, this one relies on caricature and a failure to make crucial distinctions. First, we must distinguish between the content of moral obligations and what gives them their obligatory force. Divine command pertains to the latter issue but not the former. Second, it is erroneous to assume that linking morality to divine commands renders it arbitrary, a product of capricious divine fiat. This might be true if we view divine commands through the lens of Ockham’s voluntarism and nominalism, but it is not the case if we accept, following Aquinas, that will follows upon intellect, meaning that God always acts in accordance with reason. Third, this does not imply that what determines the content of morality and God’s rationale for commanding as He does is independent of Him.

The actual situation, then, is this: what is good or bad for us is determined by the ends set for us by our nature. Given the essentialist metaphysics to which Aquinas is committed, this means that there are certain things that are absolutely good or bad for us, which even God could not change (since God’s power does not extend to doing what is self-contradictory). Now, God, given the perfection of His intellect, can in principle only ever command in accordance with reason; thus, God could never command us to do what is bad for us. Hence, the first horn of the Euthyphro dilemma is ruled out: God can never command us to torture babies for fun because torturing babies for fun is the sort of thing that, given our nature, can never in principle be good for us. However, the essences that determine the ends of things – our ends, and for that matter the end of reason too as inherently directed toward the true and the good – do not exist independently of God. Rather, given the Scholastic realist understanding of universals, they pre-exist in the divine intellect as the ideas or archetypes by which God creates. Hence, the second horn of the Euthyphro dilemma is also ruled out.

Also, remember that, in the “evil-god challenge,” the metaphysics underlying the arguments for classical theism leads to the conclusion that God is not merely a good thing among others but rather Goodness Itself. Given divine simplicity, this means that what we consider the distinctive goodness of a human being, the distinctive goodness of a tree, the distinctive goodness of a fish, and so on – each associated with a unique essence – all exist in an undifferentiated way within the Goodness that is God. As I expressed in an earlier post, “in creation, that which is unlimited and perfect in God comes to exist in a limited and imperfect way in the natural order... The divine ideas according to which God creates should, therefore, be understood as the divine intellect’s grasp of the various ways in which the divine essence might be imitated in a limited and imperfect fashion by created things.”

Divine simplicity also entails, of course, that God’s will is God’s goodness, which is His immutable and necessary existence. This means that what is objectively good and what God wills for us as morally obligatory are truly the same thing considered under different descriptions and that neither could have been anything other than they are. There can be no question then, either of God having arbitrarily commanded something different for us (such as torturing babies for fun, or whatever) or of a standard of goodness existing apart from Him. Once again, the Euthyphro dilemma is a false one; the third option it fails to consider is that what is morally obligatory is what God commands in accordance with a non-arbitrary and unchanging standard of goodness that is not independent of Him.

Now, let us return to the question of whether God has obligations to us. To be obliged is to be subject to a law, where, as Aquinas says, “a law is imposed on others by way of a rule and measure” (ST I-II.90.4). Moreover, “the law must regard principally the relationship to happiness,” that is to say, the realization of what is good for those under it (ST I-II.90.2). However, God has no superior who might impose any law or obligation on Him; there is no good He needs to realize since He is already Goodness Itself and therefore already possesses supreme Beatitude. Accordingly, there is no rule or measure outside Him against which His actions might be evaluated. He is not under the moral law precisely because He is the moral law. “[A]ll that is in things created by God, whether contingent or necessary, is subject to the eternal law: However, things pertaining to the Divine Nature or Essence are not subject to the eternal law but are the eternal law itself” (ST I-II.93.4, emphasis added).

To understand what this means is to comprehend that God can only will what is good for us. As noted above, God wills only in accordance with reason, and it would be perverse and irrational to will the creation of something without also willing what is, by its nature, good for that thing. If “nature does nothing in vain” (Aristotle, De Anima III.9 432b21), then neither does God, the Author of nature. He allows evil, but only because He can bring good out of it (ST I.2.3). Thus, Aquinas states, “as ‘it belongs to the best to produce the best,’ it is not fitting that the supreme goodness of God should produce things without granting them their perfection. A thing's ultimate perfection consists in the attainment of its end. Therefore, it belongs to Divine goodness, as it brought things into existence, so to guide them to their end.” (ST I.103.1)

In this way, God loves us perfectly because to love is to will another’s good, and God cannot fail to will what is good for us. Since moral goodness concerns the will, it follows that God is morally good- and perfectly so. However, His moral goodness is not like ours, as it does not involve fulfilling obligations, acquiring virtues, or similar concepts. Contrary to what some theistic personalists seem to believe, this does not make His moral goodness in any way inferior to ours; it makes it infinitely superior.

Does Morality Depend On God?
Not in the way many people think. Many students ask this question in class and in general conversation.
Some philosophers argue that if one accepts Aristotelian essentialism, they should be open to the possibility that morality can have a foundation even in the absence of God. From an Aristotelian perspective, what is good for a human being—and how we should treat them—is determined by human nature, which exists independently of God's existence.
This is mainly correct, although I would qualify his statements in ways I will explain shortly. As I argue, it is not atheism itself that directly threatens the very possibility of morality. Instead, modern atheists typically endorse a mechanistic or anti-teleological (thus anti-Aristotelian) view of the natural world, which they misleadingly believe has been validated by modern science.
From an Aristotelian perspective, teleology or final causality is inherent to the natural order in ways that it is not for artifacts. To illustrate, a hammock made from liana vines does not inherently possess its hammock-like function; instead, that function is externally imposed by an artificer. In contrast, the vines innately exhibit their liana-like tendencies simply by being liana vines. These tendencies arise from their nature or substantial form, whereas the hammock-like tendencies do not originate from this nature; instead, they result from a merely accidental arrangement (in the technical Aristotelian sense of “accidental”). Consequently, what is good for a liana vine—what constitutes its flourishing as a living thing (taking in water and nutrients, exhibiting a specific growth pattern, etc.)—is determined by the ends that emerge from its nature or substantial form.
Natural law theory, as understood in the Aristotelian-Thomistic (A-T) tradition, presupposes an understanding of natural objects. Human beings, like all natural substances, possess a nature or substantial form, and what is good for them—what constitutes their flourishing—is determined by the ends or final causes that arise from their nature or substantial form. Just as we can generally ascertain the efficient causes of things without reference to God, we can also identify the final causes of things without invoking Him. Therefore, just as we can study physics and chemistry without appealing to God, we can study ethics without direct reference to Him, at least to a significant extent. Since we can know what is good for a thing if we understand its nature, and we can discern its nature through empirical investigation guided by sound (A-T) metaphysics, we can derive much of the natural law from the study of human nature alone. That is why it is called natural law. As Philippa Foot (2001) argues, goodness, or at least the possibility of it, is inherent in us (Natural Goodness).
From an A-T perspective, human beings, liana vines, and everything else could not exist for even a moment unless God sustains them in existence. They also could not possess causal power for an instant unless God, as the first cause, bestows that power upon them at every moment. This is precisely what A-T versions of the cosmological argument establish when properly understood (Feser, Aquinas, ch. 5). Similarly, natural phenomena could not display the teleology or final causality they do unless God constantly directs them toward their ends, which is what the Fifth Way demonstrates when properly understood (Aquinas, Summa Theologiae, I, q. 2, a. 3). However, just as A-T versions of the cosmological argument do not suggest that natural objects lack real causal power, the Fifth Way does not imply that natural objects lack inherent teleology. Using traditional metaphysical terminology, the existence of secondary causes is perfectly compatible with the A-T view that all natural causes must ultimately derive their causal power from God. A-T firmly rejects occasionalism. Likewise, the reality of immanent or “built-in” teleology, as Aristotle understood it, is fully compatible with the notion that all teleology ultimately derives from God.
The term "ultimately" is crucial here. Secondary causes are real, which allows for the possibility of natural science. When we study the physical world, we examine how physical entities behave according to their nature, rather than through the unpredictable acts of God. Similarly, the reality of immanent teleology supports the existence of natural law. In studying ethics, we analyze what is good for human beings based on their nature, rather than on arbitrary divine commands. Ultimately, the facts examined by science and ethics rely on God, as everything depends, at every moment, on Him. In that sense, science, ethics, and everything else depend on Him. However, on a practical level, ethics can often be pursued without referencing God, just as natural science can. In this context, many moral truths would still hold even if, hypothetically, God did not exist—much like the periodic table of elements would remain unchanged. This discussion is further explored in Aquinas (Feser, ch. 5) and in Cronin’s The Science of Ethics (vol. 1, ch. 8).
That said, God remains central to ethics. For one, only part of the natural law can be understood without reference to Him. Moral prohibitions against murder, lying, adultery, and dishonoring parents, for instance, can be derived from an examination of human nature alone. However, God's existence carries its own moral implications, and since it can be known through natural reason, certain religious obligations—such as the duty to love God—can be rationally understood and thus become part of natural law. Indeed, these represent the highest obligations under natural law. Furthermore, for A-T, a complete account of moral obligation requires reference to God as legislator, even if moral obligation can be explained proximately by the natural end of the will (Aquinas, Summa Theologiae, I-II, q. 91). Finally, divine revelation is essential for a full understanding of moral life, both because human intellect is too frail to reliably discern all moral truths and because certain aspects of natural law are so demanding that many people can realistically adhere to them only with the promise of a reward in the hereafter (Cronin, The Science of Ethics).
Since much of morality’s foundation and content can be understood through studying human nature alone, it follows that morality would largely remain intact even if human beings existed without God. From this perspective, morality is not based on arbitrary divine commands, just as scientific laws are not simply the result of divine whim. From an A-T standpoint, the simplistic form of divine command theory—which asserts that moral principles depend solely on divine fiat—is as problematic as occasionalism (Feser, The Last Superstition).
As I argue elsewhere, atheism itself is not a direct threat to morality. Atheists who accept Aristotelian essentialism may still affirm significant portions of natural law. Similarly, an atheistic Platonist—if such a position could be coherently maintained—might also uphold moral realism. However, a completely anti-essentialist, anti-teleological view of reality that reduces nature to mechanistic processes devoid of intrinsic purpose undermines the very possibility of objective moral values. Since modern atheism tends to embrace this radically mechanistic worldview, it is, to that extent, incompatible with morality itself.