You aren't supposed to be asking this, since it requires addressing an unprovable and inaccessible logical substructure upon which all of 'atheistic science' rests and out of which it has developed its more demonstrable surface hypotheses and theories.
We must essentially take a giant bite into this proverbial turd sandwich every time we just 'accept' a new scientific theory. The surface theories are comparable to telling us how delicious the bread, organic lettuce, tomatoes and mayo is while giving us a long-winded version of how each is grown or made to make it all seem more impressive.
In order to actually accept the 'Big Bang' as the origins of the current cosmos, we need to first embrace that there are natural immutable laws that have no explanation and must have been here for all eternity past guiding the formation of the 'super dense point' in space and time without any 'help' from anything other than their own immutable characteristics. We must then accept that these same immutable laws, (established by nothing), continued to act upon this 'super dense point' until it unfolded and gave rise to all matter and energy forms in the entire universe, still without any 'guidance' or models to follow other than its own immutable characteristics, (established by nothing).
That acceptance does not even address the later 'super luck' required to spontaneously generate life like a tiny Frankenstein monster from out of non-biology under their same immutable impulse and characteristics.
I find the entire thing to be ludicrous, though having autism or smoking lots of recreational weed would probably help it sound more believable and 'taste' better.