proof, please.
And you have every right to doubt it, as does anyone else. That is because the big bang theory is presented as a theory. A hypothetical scenario which seems possible according to the facts we know. No one subscribes blindly to it, and every time the theory is successfully attacked - it is modified.
Likewise, Tthere isn't one scientist in the world, or atleast not a respectable one, who accepts the theory of evolution as being without fault. But that is what is convenient about that state of mind, it's open to changes and adjusts it's beliefs according to what new analysis of empirical data shows. The Catholic Christian belief is a universal belief, it's immovable because it's entire foundation is over 2000 years old. If you try to circumvent that fact, you transcend Christianity and become something else.