In some of the comments, a theme keeps showing up: Theism (especially the Christian variety) seems guilty until proven innocent; while atheism seems innocent until proven guilty. Why is this? This is known as the “presumption of atheism.” But should Atheism be the default setting? One of the leading Philosophers of Religion of our day, William Lane Craig, shares why it should not be:
“….another philosophical relic is the much-vaunted presumption of atheism. At face value, this is the claim that in the absence of evidence for the existence of God, we should presume that God does not exist. Atheism is a sort of default position, and the theist bears a special burden of proof with regard to his belief that God exists. So understood, such an alleged presumption seems to conflate atheism with agnosticism. For the assertion that “God does not exist” is just as much a claim to knowledge as is the assertion that “God exists,” and therefore the former requires justification just as the latter does. It is the agnostic who makes no knowledge claim at all with respect to God’s existence, confessing that he does not know whether God exists or does not exist, and so who requires no justification. (I speak here only of a “soft” agnosticism, which is really just a confession of ignorance, rather than of a “hard” agnosticism, which claims that it cannot be known whether or not God exists; such a positive assertion would, indeed, require justification.) If anything, then, one should speak at most of a presumption of agnosticism.”
If there is a default setting, it is agnosticism, not atheism. In that case, the atheist has just as much explaining to do as the theist.
For a more detailed treatment of this issue, see Scott A. Shalkowski, “Atheological Apologetics,” in Contemporary Perspectives on Religious Epistemology, ed. R. Douglas Geivett and Brendan Sweetman (Oxford: Oxford University Press, 1992).