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

A belief in a god is not the problem.

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

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?

Should any books be banned from school libraries? Why is it important for students to read certain books in school?

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

THE BIBLE IS 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.

15,000 Light-Years Away, Something Is Blinking – And It Might Rewrite Physics - SciTechDaily

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

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

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

'JC, Take the Wheel!' Kevin Smith Looks Back on His Hilariously Heretical 'Dogma' 25 Years Later - Rolling Stone

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

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

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

Why do companies cull employees during financial downturns without saying so?

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