Let's say that science proves that God exists

[Esquilax]

Hello Stimbo

The atheist worldview, whether individual atheists own up to it or not, is that our existence and that of the universe was the result of mindless mechanistic forces that never intended either the universe or us to exist. That worldview has significant impact philosophically speaking.

Don't try to tell us what we believe, Drew. That doesn't work out well for any of us. We'll let you know what we believe. Atheism makes exactly one claim: there is no compelling evidence for the existence of a god yet.

Do most atheists subscribe to the current scientific model of the Big Bang? Yes, but only because that's where the evidence leads. And note that I had to qualify that as "most," because not all atheists agree on that. There's no standard atheist perspective beyond that there isn't enough proof to justify a god, and so blanket statements are more than useless.