Ok... There seems to be a lot happening here and I just read the posts diagonally.
So I'll not actually dwell into the theories pertaining to the beginning of the universe. Although the big bang is still the most widely accepted hypothesis and the one with most experimental/observations facts backing it up.
The major problem with cosmological theories of the beginning of the universe is how to actually corroborate them. Mathematical models and computations simulations are all fine, but at the end of the day, experiments and observations are what sustain a theory. That's the main issue with string theory and loop quantum gravity. We just don't have the technology to actually test and confirm them.
Basically every year there's a new idea on how the universe started and how to explain stuff that isn't predicted by current theories. Then comes the part to find non-mathematical proof, and most of those ideas just go down the drain.
But to those that don't believe in the big band, I need to ask:
why?