Why does it matter so much to atheists that God doesn't exist?

I am speaking to the US Bible thumpers here, of course ~ many of whom are flat-earthers who deny evolution and see scientists as evil people who are constantly trying, and succeeding, in disproving their beliefs one by one.

The people of the modern world have evolved past all of that nonsense.

IT does not matter, mainly because it does not exist.

How Creatine Became So Popular With Women - WSJ

Notice that I said their rules, not any gods rules.

My problem is that people who try to shove their rules down everyone's throats - including by physical force - DO EXIST .

THE BIBLE IS THE PROBLEM!

Djokovic vs Norrie: Things we learned - Roland Garros

Because these are not any gods rules we are talking about.

I do not personally care if you believe in a god or not.

These are man made rules - made thousands of years ago for the use of the humans who lived thousands of years ago.

Can someone write me a sex story?

And how do you deny hundreds of years of advancement in all fields of science?

Those rules that you are trying to reinstate are rules made by men who didn't know anything about the earth, nor anything about all of the other inhabitants of it. How can you not see that?

A belief in a god is not the problem.

Why are so many people getting sick from eating cucumbers? - NBC News

And then use and ENJOY these fantastic scientific advancements every single day of your life?