You see the Christian presuppositionalist's 'reasoning' is derived from their basic presuppositions from which they refuse to budge no matter what counter-reasoning is presented by their opponent. They take for granted the truth and reliability of the Christian Scriptures and assume from the beginning the supernatural revelation of the Bible as the ultimate arbiter of truth and error. They then try to show how belief in the Christian God, Jesus, the Bible, the 'miracles', etc, is supposedly more reasonable than non-belief in those things. Amazing, really. You see, in light of their presuppositions about things metaphysic they see all thinking on such matters---well, at least their thinking---as being wholly receptively reconstructive of their (note this---narrow, emphatic evangelical) interpretation of what is set forth in the Bible as supposedly being God's Word (that is, God's thinking).
In at least one of the debates in which I participated my opponent told the audience that, given my rationalistic worldview, I was simply incapable of entertaining any worldview of a 'supernaturalistic' kind. In other words, he was accusing me of presuppositionalism---of a naturalistic, rationalistic kind. Not so. I do not start with any such presupposition. My present position is simply that the physical world in which we live yields no credible or reliable evidence of 'supernaturalism.' This is not a naturalistic bias on my part at all. Not at all. I repeat, I do not start from any naturalistic or rationalistic presuppositions. For example, believing that there are no good reasons for believing that God exists does not necessitate that God does not and cannot exist since mere belief is not proof that God either exists or doesn’t exist. Although I lack theistic belief my mind is not closed to the possibility of God existing, although I think that’s most unlikely. My mind is not foreclosed to reason, counter-argument or evidence to the contrary. I fear, however, that my Christian opponents' minds were foreclosed. Their theistic presuppositions could not under any circumstances allow them to rightly determine God’s non-existence from evidence. Their basic presuppositions compelled them to always interpret all evidence in a manner consistent with those absolutist presuppositions.
whom I debated in 2005 at the University of Technology, Sydney
In these debates---as in my various writings---I tried wherever possible to rely on reason and its principal ‘tool’, logic. (I must be honest. I would from time to time also employ some ridicule and theatrics well.) Now, when I use the word ‘logic’ I am referring to traditional Aristotelian logic. My opponents would then retort, ‘God is above the rules of logic.’ Really? That can’t be right. Now, for the sake of what follows, let’s assume that there is a God of the kind my learned clerical opponents claimed made the world, is watching attentively over it, and so on. How could this God be ‘above’---whatever that word means in this context---the rules of logic?
First, the assertion that God is above logic is not an a priori proposition. Where is the theist’s proof for this assertion? In fact, the theist, although rejecting the applicability of logic, always ends up applying logic, albeit wrongly. Theists tend to do that, and they end up tying themselves into knots of their own making.