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

A belief in a god is not the problem.

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

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

The doctor said 'be happy.' Music therapy can help cancer patients do that - NPR

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?

THE BIBLE IS THE PROBLEM!

Single photon detected in multiple locations simultaneously, fueling the multiverse debate - Earth.com

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

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.

How did the DMK alliance manage to keep the BJP out of Tamil Nadu politics all these years? Is the picture now changing in Tamil Nadu after the entry of Annamalai?

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.

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

Does Rosemary aroma really improve memory? Here’s what research says - Times of India

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