Who mentioned anything whatsoever about the big bang theory? There are MANY more theories out there than just the big bang.
Also, it does not take more 'faith' to believe in a theory over the idea that a being that did not need to be created because it is infinite and eternal.
There's is a very large difference between the two. A theory is usually presented with a form of evidence to support the notion of that theory. Many people around the world then work together to test the theory and gather evidence to either prove or disprove it. Experiments are constantly taking place, measurements being taken, and the theory can be accepted, changed or disproven based upon the evidence gathered.
On the other hand, religion just accepts the 'fact' that there is an eternal being that watches over us our entire life, who we are being judged by and can condemn us to eternal damnation in hellfire. Who's only 'evidence' is a 2,000 year old book, full of contradictions, 'metaphors' and morally corrupt teachings.
EDIT: This is for you, Kill.
http://www.youtube.com/watch?v=zi8FfMBYCkk