One common — and pernicious — argument against naturalistic explanations of persons is that if people are just conglomerations of atoms, then they are not morally relevant (or that they lack moral significance; herein, I will assume that ‘moral significance’ and ‘moral relevance’ are interchangeable). The point, I take it, is supposed to be that, in virtue of their composition, anything composed of atoms would fail to have the right sort of properties to be morally relevant (whatever those sorts of properties are). For example, Christian apologist Brian Colon writes, “If all that exists is matter, then that would mean that we are nothing but matter as well. If that’s true then why do we believe that humans are worthy of respect? […] Humans really are worthy of respect. This is inexplicable on the Atheistic Worldview.”  Call this the atomic objection. In this post, I will show that the atomic objection fails spectacularly and argue that theists should not advance the atomic objection against their atheistic interlocutors.
1. What’s so wrong with being composed of atoms?
At minimum, the theist needs to do more work to spell out exactly what the atomic objection is supposed to be, or why it’s so objectionable to think that humans are composed of atoms. Notice that one way to make humans sound morally insignificant is with locutions of the following sort: ‘humans are just x’, where x can be filled in with whatever humans are taken to be composed of. For example, the materialist might say, “humans are just atoms in motion”, and this sounds rather deflationary and depressing. But the same could be said of their supernaturalist rivals — “humans are just immaterial souls” or “humans are just immaterial minds created in the image of God” or whatever — and it would sound just as deflationary and depressing. Therefore, one cannot simply list the component parts of humans and, from that list, surmise whether humans have some sort of moral significance. Instead, one needs to show that given their component parts, humans either can or cannot have attributes which endow them with moral significance.
Moreover, any property theists claim we possess in virtue of having a soul — the ability to form rational thoughts, or the ability to appreciate love or goodness, or whatever else — are likewise properties the atheist will attribute to our having minds, ultimately reducible to a particular kind of brain. If the theist claims physical matter cannot have thoughts, the ability to appreciate love, and so on, on the basis that they cannot see how physical matter could possibly perform those sorts of processes, the atheist is free to point out that they cannot see how the possession of a soul allows us those properties either. The theist can maintain that the soul performs those processes in ways mysterious to humans, but the atheist can just as easily maintain that the brain performs those processes in ways equally mysterious.
This impasse between the theist and atheist can made rigorous through a famous argument schema called the Moorean shift.
1a. The Moorean Shift
Since Rowe’s 1979 article “The Problem of Evil and Some Varieties of Atheism” , theists and atheists alike have noted that the problem of evil can addressed, by the theist, through a Moorean shift. In what follows, I will explain what Moorean shifts are, how they apply to the problem of evil, and finally show that the theistic objection I’ve been discussing in this post can be subjected to an atheistic Moorean shift. Arguments of the form :
3. Therefore, r.
Can be responded to with parallel arguments of the form:
4. Not r.
6. Therefore, not p.
Shifting from 1-3 to 4-6 is termed a Moorean shift. The idea is that arguments like 1-3 are sometimes just as rational to maintain as arguments of the form 4-6. William Rowe maintained that theism and atheism can both be rational positions, depending on how one formulates the problem of evil. In a 2007 article, William Lane Craig follows Rowe and offers the following rendition of the problem of evil (where I’ve re-numbered the premises) :
7. If God exists, gratuitous evil does not exist.
8. Gratuitous evil exists.
9. Therefore, God does not exist.
Still following Rowe, Craig suggests the Christian can provide the following Moorean shift (again, with re-numbered premises):
7. If God exists, gratuitous evil does not exist.
8*. God exists.
9*. Therefore, gratuitous evil does not exist.
Craig notes that premise 7 is uncontroversial between atheists and himself and explains that premise 11* can be maintained, by the theist, by appealing to independent arguments made on behalf of theism (such as the Kalam cosmological argument, the argument from contingency, and the moral argument). I’ll put aside whether Craig is right to maintain premise 8*. Supposing Moorean shifts are legitimate responses to apparent defeaters, objections the atomic objection can be similarly Moorean shifted by the atheist. For example, one way to state the atomic objection is as follows:
10. Nothing that is composed solely of atoms can have moral significance.
11. Atheists maintain that humans are composed solely of atoms.
12. Therefore, atheists should maintain that humans have no moral significance.
However, atheists are unlikely to accept premise 10. In fact, atheists are free to perform the following Moorean shift:
10*. Atheists maintain that humans have moral significance.
11. Atheists maintain that humans are composed solely of atoms.
12*. Therefore, atheists should maintain that some things composed solely of atoms have moral significance.
Here, atheists can maintain 1o* on the basis of independent arguments for secular moral realism or secular moral significance, just as Craig maintains 8* on the basis of independent arguments for theism. The theist cannot object that 1o* is question begging, unless they concede that 8* is likewise question begging.
2. Does our being created by God grant more moral significance to us than our not having been created by God?
The theist might try another approach. On Christian theism, humans were created for specific purposes and perhaps this explains why humans are more morally significant than they would be on atheism. On this account, humans have the proper sorts of lives when they maximally fulfill the purpose for which they were created and, when they fail to fulfill the purpose for which God created them (that is, when they fail to fulfill their telos), they fail to realize their greatest happiness. Moreover, humans have moral significance because they were created in the image of God — and so they resemble God in the appropriate ways, which includes their being non-physical, rational, free minds. In contrast, if there is no God and if humans are mere conglomerations of atoms, then they were not created for a purpose, have no telos to fulfill, and are not non-physical, rational, free minds. On this view, humans are morally significant because they have the requisite attributes to lead lives that are meaningful or purposeful in some important sense.
First, as already discussed, this version of the atomic argument can be responded to with a Moorean shift. The atheist maintains that humans are rational, free minds while simultaneously maintaining that they are composed of atoms not created by God and can appeal to secular arguments for moral realism and moral significance.
Second, the mere existence of someone who created oneself for some purpose does not suffice to provide one’s life with purpose in the relevant sense. All of us have parents who, presumably, brought us to life for whatever purposes they possessed. But it would be strange to say that we should always embrace our parents purposes as our purposes. Perhaps one’s parents wished that one become a doctor, but one is happiest if one is a philosophy professor. For the theist to claim that God having created us endows our lives with purpose in the relevant sense, the theist must maintain that God differs from parents in some relevant way.
One proposal might be that God recognizes some Good we might fulfill and has designed us in such a way that we would be maximally happy if we were to fulfill that Good. There are three metaphysical possibilities for the existence of such goods: a. such goods exist independently of God; b. such goods exist as a consequence of God’s will; or c. such goods can be identified (somehow) with God’s nature. I turn to each of these in turn to show that none of them succeed.
a. The first possibility: there are goods independent of God, but which God recognizes and has designed us so that we might fulfill them. Here, the problem is two-fold. First, by construction, none of these goods can exist as a result of God’s will or nature and therefore must not have been created by God. But, due both to God’s aseity and to central Jewish, Christian, and Islamic doctrines, nothing exists independently of God. Second, if there are goods, in virtue of which we might be maximally happy, independent of God, then such goods — because they are God-independent — can exist with or without God. Therefore, human lives could be meaningful — and thus morally relevant — on any atheist view which allowed for the existence of the Good.
b. The second possibility: the Good towards which our lives are to be properly directed is the result of God’s will. However, one might ask what sort of reasons God possesses for so directing us. Such reasons cannot involve a prior recognition of the Good, for such goods, and that we should be directed towards them, is the result — and not the cause — of God’s will. And, by construction, such goods cannot be somehow identified with God’s nature (though I will later consider the possibility that the Good is to be identified with God’s nature). Thus, it seems that such willings would be totally arbitrary and without reason if they only existed as the result of God’s will. Again, this is troubling for the theist, because willings without reason are random; God might as well have directed our lives towards evil or axiologically neutral states of affairs.
c. Finally, the theist might maintain that God directs our lives towards Good, where the Good is (somehow) identified with God’s nature. States of affairs which are maximally good, in the axiological sense, are those which maximally resemble God’s nature. However, it is fairly difficult to make sense of this view. What could it possibly mean to say that some creaturely state of affairs — which, like all other creaturely states of affairs, is infinitely distinct in every respect from God — somehow maximally resembles God? Christian philosopher Mark Murphy remarks:
[Craig] offer[s] no account […] of exactly how God’s nature provides the relevant standard [of goodness], a fact which is treated as an important consideration against nontheistic accounts of the nature of moral value. In reply to Craig, a number of writers suggested that a standard nontheistic account treats moral value as grounded in prudential value — what is good for persons — but as valued from an impartial perspective, one that takes into account all of the persons who can be made well or badly off. Craig rejects this view, claiming that it is not straightfowardly entailed by the existence of prudential value and the capacity of humans to take this impartial point of view that there is anything like moral value. But of course neither is it straightforwardly entailed by the proposition that God exists that there is anything like moral value. What we have here is a classic example of uneven standards being applied to the debate at hand, treating an appeal to God as able to fill an explanatory gap when it is far from clear that this appeal succeeds any farther than a nontheistic account does. 
Thus, for Murphy, grounding the Good towards which our lives might be directed in God’s nature is left mysterious by the theist. Moreover, if the theist can appeal to divine mystery to explain philosophical difficulties, the atheist can just as well appeal to naturalistic mystery. The God of the Gaps is just as good an explanation as Nature of the Gaps.
But I think the situation is actually worse for the theist than Murphy indicates. As traditionally conceived, God’s nature is radically unlike anything in the created realm. To say that God transcends the created realm is at least to say that God is infinitely different from the created realm. So what could it possibly mean to say that a state of affairs is good if the state of affairs appropriately resembles God? Any given state of affairs, at least in the creaturely realm, will always differ infinitely from God; so are no states of affairs good? But then what would it mean to say that one’s life might be appropriately oriented towards the Good?
We’ve seen that the atomic objection does not succeed in showing that atheists are inconsistent if they posit humans to possess moral significance. At best, in positing the atomic objection, theists show that atheists are left appealing to mystery, but theists equally appeal to mystery in their claim that souls are morally significant. Either way, one maintains that substances — whether spiritual or physical — are somehow endowed with moral significance. Moreover, claims that only a spiritual substance created by God could be endowed with moral significance are left either allowing for atheistic moral significance, positing that persons are somehow only randomly morally significant, or with only more mystery.
 Colon, B. (2010) “Atheism a Failed Hypothesis”. On the Evidence for Christianity website. http://evidenceforchristianity.org/atheism-a-falsified-hypothesis/
 Ibid, pp 338-9.
 Craig, W. (2007) “Theistic Critiques of Atheism”. In Cambridge Companion to Atheism (Cambridge: Cambridge University Press): 69-85. Also see the online expanded version.
 Murphy, M. (2004) “Suarez’s ‘Best Argument’ and the Dependence of Morality On God”. Quaestiones Disputatae, 5(1): 30-42. Block quote is from pp 32-33.