Why theists boast so much about their religion and existence of god when logically they have no real proof?

Whenever you read their answers on Y!A, you notice that they just give references from bible. What is the proof that whatever is written in them is true. They just chose to believe blindly what elders taught. Do they ever think logically about all this. When we need logical & scientific reasons to expain scientific phenomenas, then why not for all these things like god's existence, etc. Will they ever think logically?