A Core Problem With Atheism

Question:: 
While I certainly respect your right to believe as you wish, I have a real problem with explaining the universe.... If matter is eternal (as it must be, if there is no God), then that means that matter has existed for an infinite period of time. That means that during that infinite amount of time, infinite configurations have come and gone, come and gone. That means there have been infinite numbers of universes, infinite numbers of EARTHS, and infinite numbers of IDENTICAL humans/existences. After all, this expand/deflate thing has been going on for UPTEEN TRILLION CENTURIES...if matter is what is eternal. Now, for the athiest, this might be perfectly acceptable. But for me, it is not. BOTH takes--eternal matter or a First Cause God--are matters, to some degree, of faith. We simply don't know. I am wondering how the atheist deals with the prospect of an eternal universe? Does it have any affect on the position, or does it not even matter? And if not, why not? Thank you for your time!
Atheist Answer: 

Actually, there's just one thing about your concept of an eternal universe which needs addressing: the "expand/deflate thing" probably isn't true. The universe isn't slowing its expansion, it's speeding up. That means it will never shrink back to a Big Crunch, and this particular universe isn't cyclical in the way you imagine.

That doesn't stop the universe or multiverse from being eternal in other ways, so the question is still valid.

The law stating that matter and energy cannot be created or destroyed does suggest all by itself that the universe is eternal. This does not necessarily mean, however, that all possible universes have already happened. It may go along some form of cycle. To demonstrate, take a calculator, enter 1 and then multiply it by -1. Then multiply the answer by -1, over and over again. You'll only ever get -1 and 1. You certainly won't get all possible numbers.

You're right, we don't actually know whether the universe is eternal. Even if it isn't, though, it doesn't guarantee the existence of a god or even a First Cause. This is because of two things:
1. This universe's time is highly unlikely to have been entirely linear and consistent around the Big Bang.
2. The probabilistic behaviours of particles according to quantum mechanics have no discernible cause at all. It's just possible that not everything in the natural world even requires a cause.
With time and causation themselves in doubt, the First Cause argument is a bit of a moot point.

As for which is more plausible out of an eternal universe and an eternal god, that's up to each person. I think of two things: the fact that before the Big Bang theory the most popular one was an eternal "steady state" universe, and the fact that an eternal, uncaused, uneducated god makes eternity all the more mysterious and unfathomable. Whatever the universe got up to in all that time, at least we can imagine some of it. With a god, we haven't a clue.

- SmartLX