Many people think the Big Bang theory says that the universe sprang from nothing. Moreover, they think the Big Bang theory was invented - out of thin air - purely so that scientists could avoid the self-evident fact that God created the universe.
Well, that’s not how the Big Bang theory came about, and in fact the Big Bang theory is not even about the origin of the universe.
We can see that the universe is expanding. That means it must have been smaller (actually “denser” is a better way to look at it) in the past, right? Seems pretty sensible, right? Nothing outrageous, no denying self-evident truths about God, just a straightforward (or straight backward, actually) extrapolation from observed facts. With me so far?
Congratulations, you now accept the Big Bang theory! (that wasn’t so bad, now was it?)
Despite what you may have heard, the Big Bang theory has nothing to do with how the universe was created - it’s simply a description of how a very dense, very hot, region of spacetime could have expanded and cooled off to produce what we see today. It’s called the Big Bang theory to distinguish it from the now-discredited Steady State theory, which proposed that the universe was NOT denser in the past.
Where did that early universe come from? No one knows! The Big Bang theory has been tracked backwards to a tiny fraction of a second after the universe came to be - and if it’s true, then there would be observable consequences today, like the Cosmic Microwave Background. When we look at the CMB, we see exactly what we’d expect to see if the universe really did expand from a very hot, very dense, starting configuration. So we’ve got good reasons to think we’re on the right track.
Maybe God did create that early universe. Or maybe he created our universe 6,000 years ago, and just created all the galaxies flying apart to fool us (though one wonders why God would basically lie to us like that). Or maybe he created the universe at midnight last night - not only creating galaxies in a “flying apart as if they had been together ~13.8 billions years ago” configuration, but creating the neurons in your brain in the same configuration they would have been in had you actually grown up, went to school, had your first kiss, etc.
All of those things are technically possible - but until/unless there’s any evidence for them (spoiler: there isn’t), science can’t really do much with those ideas. Science doesn’t say there isn’t a God, it just says that most things don’t seem to really need a God.
It’s like plumbing: there are religious plumbers, and atheist plumbers - but they all need to know that water flows downhill. There’s no obvious benefit to having a religious plumber - he can’t “bless” your pipes and make them better somehow. When you go to plumbing school, they don’t deny that there is a God - but I guarantee you it never comes up in class, because there’s just no need for a God in plumbing. It’s the same with cosmology.