[Note: This is an actual email exchange (minus the last comment) between a very well-known Christian apologist and myself. No, it's not Craig or anyone else in the U.S. or the UK. Hopefully you Oprah-idled mentalities can make the analogy between the above graphic and the circularity of many believers in arguing for God's existence.]
Atheist: I ask you believers a question about logical justification and you just give me either an unargued ontological claim or else an ontological if-then conditional that still puts you in the position of assuming what is in question. A very dangerous thing to do in any area of inquiry.
In terms of the source of logical authority, the standards of analysis themselves are already God-level, and you don't need God to either believe them or effectively use them for any and all purposes and areas of thought and knowledge, in acquiring and verifying truth.
In fact, when it comes to adjudicating the question of God's existence, those criterial standards are higher in belief-deciding logical authority than any God could be conceived of being, because they are assumed to be the ultimate tolls for deciding the legitimacy of any conclusion in deciding God's epistemic fate in the minds of sentient beings.
To give reasons for X necessarily is to assume that those reasons have a higher logical authority than X, whether X is "God exists" or "A tumor exists next to Frank's heart". Reason must necessarily determine God's ontological status, and is therefore the God of mind, and equally to the theist apologist. That's why arguments are constructed in the first place: to get some logically higher-level authority about which conclusion to come to.
Consequently, because one need not believe in God to efficaciously use those rational standards, atheism wins by logically prior default, and the fact that apologists for God themselves use principles of thought that do not require belief in God is a tell-tale implicit admission that reason is the highest court of appeal, not God. Therefore, not only is the truth of atheism assumed by all parties that argue their respective cases, but all arguments for God are based on atheistic principles of rationality.
Therefore, atheism is true both existentially as a prior temporal but enduringly necessary assumption going into the debate about God, and also logically prior as necessarily presupposed in order to argue about whether there is a God."
Christian Apologist: Your conclusion does not follow from the premises.
The fact that one starts on a common ground of rationality with the atheist does not establish rational argument as more ultimate than God and thus make God superfluous. One thinks of the parallel presuppositionalist argument--e.g., Gordon Clark's viewpoint--that one must start with the God of Scripture in order to justify rational reasoning.
What apologists such as I are doing is simply to employ the common rationality that all humans do in fact (and must) use to make sense of the world we all live in. Rationality tells you something about human beings, but nothing necessarily about the existence of God, pro or con. One uses that rationality to show factual grounds for God's existence over against atheism.
To make the rationality itself ultimate would be like making a map ultimate--rather than the city to which one wished to go and found directions using the map. The map is a means-to-an-end; the fact that one starts with it doesn't make it somehow superior to the city itself. Reasoning is a "presupposition of method," a working hypothesis, that can lead to factual information.
Once one has shown God's existence factually (by the contingency argument, by the case for Jesus' deity, etc.), one can then argue that the God in question is rational and the source of rationality--for otherwise there is no adequate explanation for human rationality or for God's employment of rational revelation to communicate with his creatures and provide a means of salvation for them.
Atheist: Dude, you're using reason to argue that reason is not ultimate, as if reason is in fact the ultimate authority of your thinking after all.
