Stump the Christian?

[Jackalope]

M-Theory (despite the name), is currently a hypothesis, not a scientific theory.

The "Big Bang" Theory is absolutely testable and falsifiable.

Your classification system needs work.

Interesting.  I would like to hear how you would test it for falseness.  To my knowledge there is supporting observation evidence of the theory.  But this is not the same as being testable of falsifiable.

The theory makes (by implication) several predictions of what we ought to observe.  If we have the capability of making those observations, and what we observe is not what was predicted, viola the theory is falsified.

As an example, the theory implies what we ought to observe regarding the uniformity of the cosmic microwave background.  Had the observations not conformed to the predicted, the theory would have been falsified.  The observations do match, however.