What makes the big bang a creditable scientific theory is that from that theory predictions can be made, experiments derived to test the predictions, tests carried out, and the theory refined in light of the new information.
Scientific theories aren't "this is the truth" things, they are "this theory best explains XYZ to the best of our current understanding".
It is perfectly reasonable to think that the research into the origins of the universe might just lead us to God. Of course it might lead us away also.
What isn't reasonable is to say that ID is a scientific theory as you can't come up with predictions based off of it, or tests to prove/disprove those predictions, etc.
ID is a belief. As a belief there is nothing wrong with it, it is a belief I personally hold.