Atheists: Why do you deny that the universe existed infinity years ago?

Atheists do not believe in gods. That's it. Atheism has nothing to do with science and vice versa. The Big Bang is science and is accepted by theists and atheists alike.

Time and space began at the Big Bang 13.81 billion years ago. As time began at that point, you cannot have a "before" the Big Bang. It is difficult to understand and even scientists do not understand it fully. We know what happened to the universe from Planck Time (a minute fraction of a second) after the BB but we do not know what happened in Planck Time, we can only surmise. Some day we might know but we don't yet.

Putting a god in there just complicates matters. There is no need for or evidence of any gods from Planck Time onwards so if you want to put a god in to fire the starting pistol as it were, that's fine - except that you have to explain where the god came from and what happens when we do know what happened and there is no room left for gods?

No atheist denies any such thing.

Atheists don't believe in the existence of any deities.

Your statement and then the "thus" conclusion have no relation to each other. So your premise is flawed.

WOW, how incredibly ignorant.

"...Why do you deny that the universe existed infinity years ago?"

"Thus, there is a God that created the physical universe a finite number of years ago..."

You DO realize, don't you, that with those two statements, you completely contradict yourself?

"Why do you deny that the universe existed infinity years ago? "

Because there is no evidence that the universe is eternal and we have good reasons to believe time began at the Big Bang.

"Thus, there is a God that created the physical universe a finite number of years ago in physical time."

Even if the universe came into existence within time, that wouldn't imply a god created it. It technically wouldn't imply any cause at all. Causality is a relationship between physical events in the universe. We have no reason to believe it applies outside the universe. But the point is moot anyway because time is a dimension of the universe. The universe does not exist within time.

And of course, if the universe is eternal, it could not have been created (at least not as an event in that same dimension of time). But I suspect your argument is not sincere and this is some kind of parody argument.

You skipped several steps in your god conclusion. You jump from time can't infinitely regress, therefore a god created time. You didn't even prove a god must and can only exist to create time and a beginning to it, you just skipped to that conclusion without proving it, and I'm pretty sure you will not understand why that is a giant problem.

Sorry, magic does not exist.

time requires space and matter/energy. no universe = no time

I don't deny that. It is cosmologists who suggest that time began at the singularity about 13.8 billion years ago. I do not have the expertise to evaluate that.

Well who should I believe?

The scientific findings of some of the finest minds the human race has produced, or some stranger posting in R&S?