You are going to hate this answer, but I'm not going to pretend.
Faith comes by hearing, and hearing by the word of God. It is after you have faith that you are saved and given the indwelling Holy Spirit, which acts as an intellectual "sixth sense" of sorts, and helps one discern the truth more easily.
You have faith when there is no proof, and then the proof presents itself to you over time, only to strengthen your faith. It's not a lifelong "I'm going to not believe until I see proof" type of thing.
I'll admit it seems backwards, but hey, all I know is that it works, at least for me. Everything just starts to make sense--it's like a steamy mirror after a shower. At first you can't see your reflection, but slowly and surely it clears up.
Obviously there is no real proof nor refutation of such a claim, and there is really not much to debate about. It's why I think religious debates between believers and nonbelievers is almost always going to be fruitless.