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

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

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

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

Why men with broken heart syndrome are more likely to die, according to experts - East Idaho News

THE BIBLE IS THE PROBLEM!

A belief in a god is not the problem.

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

Observations from Titans Minicamp on Wednesday - Tennessee Titans

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

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?

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

The Day the Earth Smiled: Earth, the Moon, and Saturn All in One Frame - The Daily Galaxy

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

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

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

Michigan International Speedway weekend schedule, TV info for NASCAR Cup, Truck, ARCA - NBC Sports

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.