Victor Reppert links to a defeasibility argument. The giver of the argument claims that it is a prerequisite of rational discourse about theism or atheism for the arguer to be able to state under what conditions he would not believe what he believes. Reppert gives one critique of the argument, but mine is different from his: even if we take a bird’s-eye view of the question of theism and atheism, putting aside the question whether one side is right, we don’t need to think that both sides must be equally ready to declare defeasibility conditions. Belief is not the same thing for a theist and an atheist since for the theist this belief is bound up with another (namely, God) while for the atheist it is not. Perhaps if we consider believing merely as an epistemic response to evidence we can insist on equal defeasibility conditions, the fact remains that there is more to, say, Christian belief than response to evidence. Belief is also a personal relationship with another, and so to ask such a person for defeasibility conditions is to ask him for the conditions under which he would sever or destroy his relationship. But not all relationships come with specified conditions under which they can be severed. You can’t ask me for the conditions under which I would divorce my wife or disown my children or nullify a federal law. I’m bound by vows and natural laws to certain relationships that don’t come with conditions for severance, or at least no condition that just allows both parties to just nicely go our separate ways.
So at the very least, there does not seem to be parity between atheist and theist defeasibility demands. The relevant belief is not a matter of personal relationship for the atheist as it is for Christians and other believers.