Nobody (seriously) presents the Big Bang Theory as some unquestionable fact that anyone who questions it is an evil sinner or something that should guide our societies and laws though. It is one of a set of ideas, hypotheses and theories based on observation and assessment of
objective evidence. as further evidence is discovered and new ideas proposed, those hypotheses and theories are updated, built-upon, changed or even replaced.
"God" isn't a scientific theory, it isn't even a hypothesis - believers can't even agree on what it actually means. It isn't based on
objective evidence and isn't open to change or correcting in the face of additional evidence.
Some people (especially lay-people with socio-political motives, including theistic ones) may well behave in a faith-like manner towards various scientific concepts but they're just wrong. Faith has no place in science (other than a topic of study under psychology
).
Also, please look up the difference between a "scientific theory" and "theory" as it is commonly used.