In my life, I’ve identified as a non-denominational Christian, theist, agnostic, atheist, and atheist plus metaphysical naturalist, in that order. … My research has led me to the conclusion that metaphysical naturalism, which entails atheism, is more probable than theism. This conclusion follows from three facts. 

First Fact. Metaphysical Naturalism Has a Higher Prior Probability than Theism. In other words, prior to examining the evidence about God’s existence, naturalism is more likely to be true. Allow me to explain.

Metaphysical naturalism and (metaphysical) supernaturalism are symmetrical claims and so have equal prior probabilities. Metaphysical naturalism and theism, however, are asymmetrical. Theism is more specific than supernaturalism but is not entailed by supernaturalism. Therefore, it follows that, before we examine the evidence, theism will have a lower prior probability than supernaturalism. (There are more conceivable ways to empirically discredit theism than there are conceivable ways to empirically discredit supernaturalism.)

Second Fact. Evidence about God Does not Favor Theism Over Naturalism.

I believe there are several specific facts which favor naturalism over theism: the fact that science can explain so much without explicitly appealing to the supernatural, the hostility of the universe to life (which is compatible with the universe having life-permitting conditions), mind-brain dependence, common descent, the biological role of pain and pleasure, and so forth. This is so even if there are other arguments which favor theism over naturalism, such as the beginning of the universe, the life-permitting conditions of the universe, consciousness, religious experience, moral agency, and so forth. I, for one, find most of these “theistic facts” completely unconvincing. (The argument from moral agency is the one exception.) Let’s assume (but only for the sake of argument) that all these theistic facts really are evidence favoring theism. Even so, when we compare the naturalist’s facts to the theist’s facts, it seems that that the theist’s facts don’t outweigh the naturalist’s facts. (At the very least, it’s far from obvious that they do.)

Third Fact. The Ambiguity of the Evidence about God is Evidence Favoring Naturalism over Theism.

This is where the work of John Schellenberg comes in, especially his recent book, Wisdom to Doubt. The objectivity ambiguity of the evidence about God’s existence is itself evidence: evidence against God’s existence. It provides an excellent reason to agree with Schellenberg’s claim that reasonable or nonculpable nonbelief exists. As a form of so-called “divine hiddenness,” the fact of nonculpable nonbelief is more probable on the assumption that naturalism is true than the assumption that theism is true.