The first point that should be made is that by claiming that the Christian faith is a historical "fact" I am not suggesting that the claims that the Christian religion makes are any less paradoxical or mysterious. My main argument in the previous post was that the authoritative sources of the Christian faith were historically provable as valid- it was not that the propositions contained in the Christian faith 1. Have to be believable in terms of the bar of human reason. 2. Are rationally understandable in and of themselves.
My attitude on this point is the same as the Lutheran Scholastics (notably Johann Gerhard) who's approach goes back to both Martin Luther and St. Thomas Aquinas.
First, the Lutheran Scholastics as I showed in previous posts have arguments proving the truth of the Christian faith. They didn't have any trouble with the idea that the sources of the faith were rationally provable.
George and Mike made a good point in an earlier post that part of the the reason why modern people are afraid of giving rational proofs of their faith is because they are afraid that secretly it's really not true after all and placing it the realm of the rational would open it for falsification. In any case, Christianity cannot avoid this since it is actually a religion about history- not a form of mysticism. That being said, there should be proofs of the authoritative sources behind the Christian faith. As I have argued below, the real proof of the Christian religion is the resurrection and one can adduce the authority of all Christian doctrine from that fact. This is totally in keeping with Jesus own claim that the "Sign of Jonah" would be the one proof of this Messiahship and everything else he claimed. So, my argument I think is good exegesis also.
The second point strikes at the actual propositional content of the faith. Is it reasonable? Aquinas would say something like this: The content of the faith is rational and can be worked with reasonably. Nevertheless, it take the foothold of faith and the knowledge of revelation to get up to that level of knowledge- but once you're there, you can use reason to understand it.
Luther would go a different direct, as would the Lutheran Scholastics. Although sources of the faith are rationally provable as true, the propositional content is above reason. God is not bounded by human reason and cannot be understood by it. Every proposition of the faith is trans-rational. So, how God could be God and then a human being is a mysterium that cannot really be picked apart rationally. Neither can it be understood how there can be one God and three persons- or how something can be bread and also the body of Christ or how a human body can be in multiple places at once and eaten by people Sunday after Sunday for 2,000 years and not run out. These are great mysteries and paradoxes. One is right to call them the "mystery of faith."
Nevertheless, they are knowable. Augustine's distinction here of "knowledge" and "comprehension" is helpful. So for example, I can know what infinity is or even, let's say, a trillion is. Nevertheless, I can't really totally wrap my mind around it. It's too much for me to think of in and of itself. Nevertheless, I have knowledge that it is a reality and what it is. I think we can say the same of the mysteries of the faith.
Do you buy this? Let me know.