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

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

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 .

Ukraine Says It Attacked Crimean Bridge as Traffic Halted - Bloomberg.com

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?

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

A belief in a god is not the problem.

Who believes that Speaker Mike Johnson will certify ‘a free and fair and legal election'? Who believes that Speaker Mike Johnson will NOT certify ‘a free and fair and legal election'? Why?

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.

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

How do you have intercourse with a girl who can remember you for a long time?

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.

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

Why does my girlfriend keep asking me if I love her?

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