that belief in God is irrational or unscientific. The converse is true... those who assert that "there is no God" are the ones relying on blind faith. Their beliefs are irrational and also rely upon a violation of the laws of science if they are to be believed.
The bottom line is that for a person truly seeking the truth, belief in a God is far more logical and probable than a blind belief that "there is no God" sans any evidence or logical basis for that belief. In fact that belief flies in the face of the evidence and logic.
But for those interested in philosophical proofs, there are plenty of those as well:
Twenty Arguments For The Existence Of God
by Professor Peter Kreeft
http://www.peterkreeft.com/topics-more/20_arguments-gods-existence.htm
Can You Prove God Exists?
http://www.peterkreeft.com/topics/gods-existence.htm