To clarify all that has gone before...
I do not think that anything that I have written achieves anything more than putting a necessary question mark against the ratio-empiricist view of the world. It proves nothing, disproves nothing. I'm happy with that as a result. Ultimately, it is only the ratio-empiricist view of the world that demands proof in this way.
If I were to begin writing this again, I could begin from a totally different point. Rather than a philosophical starting point, we could have a Biblical one. Consider the throwaway comment of the Apostle Paul in Galatians 4:9...
But now that you have come to know God, or rather to be known by God...
But this relationship, for all its genuine two-sidedness, is not symmetrical. The "or rather" is significant. It doesn't undo the first clause, but it does relativise it. Your coming to know God happens in the context of God's coming to know you. His action is decisive in a way that yours is not. He reveals himself - opens himself to personal relationship - in your direction, and you respond. Numerous other Biblical passages, in Old and New Testaments, paint the same picture.
If reality is ultimately personal, this is how it must be. Ultimate reality is personal, therefore ultimate knowledge is relational. This will never sit well with the ratio-empiricist. He demands the right to be a spectator, an analyst. From the point of view of the analyst, all of this relational behaviour can be explained away - and I should say, very successfully and tidily explained away. No person is found here. No relationship is founded here.
Why am I Christian then?
Because I am confronted by an undeniable Thou - the God who reveals himself.
I am confronted by Jesus Christ.