Since a lot of this is very clouded and messy, I suggest everyone for the sake of the pursuit of answering the question, read this exchange,
Thread: I'm an Atheist. Why should I believe in a god? Which god? and why? (Page 3)
The OP asked for a rational way to decide in believing in god.
I supplied those rational ways by famous philosophical proofs of God.

Now, it's up to the OP to read them. Otherwise, it's basically a foolish pursuit.

Practically every other post save one on proofs of God from a philosophical basis are superfluous to the discussion.
Thread: I'm an Atheist. Why should I believe in a god? Which god? and why? (Page 5)

We're not discussing the authority of Scripture or Evolution.