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

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

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?

After more than 60 years of development, here is the nuclear engine that is set to go to Mars with NASA. - Farmingdale Observer

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

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

THE BIBLE IS THE PROBLEM!

How mentally ill are Republicans who think Trump is mentally sane? He literally said immigrants eat pets.

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

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

Does centrifugal force teach us about gravity?

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?

A belief in a god is not the problem.

How can we become the best humans? How can we trust each other?

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