To believe in God is not about being gullible it is about trusting everything to him, everything that remains mystery that even scientists can't discover. Even to a person who chose to believe the Big Bang theory knows that those theory is not enough to disclose every questionable explanation and by that I think he also use the word faith by continuing believing the Big Bang and let every mystery remain and hoping that someday science can explain which is actually not. So I'd rather chose to believe the one God who created every existence than believing it came from Big Bang or evolution. I'd respect your stand and understand it. It is very hard to believe to someone which is you never seen and declared it as the Creator, but it is also hard to believe that science can explain everything and the solution which is also actually not. I believe in science but not everything that it says, since they have different explanation and view on other things.