People who replace god with the big bang havent thought about it enough.
The "why" question always leads to infinite regress.
If I would be a believer in god that actually inquires into his beliefs, I would say that god is the infinite limit of that infinite regress of questions.

There is no ultimate answer to the question "what caused the universe to be created" because to every answer that we come up with, we will be able to ask "and what caused that?". What we can do however, is define a limit that is beyond questions and language, the limit of that sequence of infinite regress questions, and call that limit "God". (What I did is just named something as "God". I havent attached any attributes to it like all powerful or all knowing)

To folks that studied math in depth to some extent, infinity is defined such as for every number M that we choose, infinity will be bigger than M. Relating it to our topic, infinity, or "God", could be defined as an answer to every question that follows the question "what caused the universe to exist". For every question "what caused X" in the infinite regress, we can say God caused it, but we can't ask "what caused God", because we define God as the limit of this sequence of questions, which is not a cause in and of itself, like infinity is not a number.

All of the above doesn't prove that there is some entity that created the universe. All it does is challenge the definition of "God" and the atheists that claim "god doesn't exist". All they do is assume a certain definition of god and try to disprove it with silly attempts. What if what religions truly originally meant by the word "God" is something totally different than what mainstream culture (and religion) thinks?