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

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

A belief in a god is not the problem.

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.

Is the Shia claim true that Imam Ali was born inside the Kaaba?

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

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

THE BIBLE IS THE PROBLEM!

Why are European countries warning European travelers to be careful traveling to the United States?

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

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

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

From the Desk of AD Laird Veatch: Mizzou Athletics Embarks on New Era With ‘Will to Win’ - University of Missouri Athletics

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

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?

Discovery of 100-million-year-old dinosaur eggs reveals life in Jurassic America - Earth.com

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