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

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?

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

Is it common for girlfriends to have close male friends who are single and not related to them?

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

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 .

If you caught a shoplifter at your yard sale, how would you handle it?

THE BIBLE IS THE PROBLEM!

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

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

Is there anything wrong with me because I'm still single?

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

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.

A belief in a god is not the problem.

How do great movie moments influence how people handle real-life moral dilemmas?

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?