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

IT does not matter, mainly because it does not 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 BIBLE IS THE PROBLEM!

Why is my ping so high in 1 Roblox game but not the other ones? I am also not laggy in my own private server. What is happening?

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

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

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

Why did Trump call Biden and Schumer Palestinians?

A belief in a god is not the problem.

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

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?

What did someone say to you that instantly made you realize their life was in danger?

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

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

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

Who was the guy that had sex with the AIDS monkey?

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