But then again, my resulting question is why, if you have already conceded that something can be eternal and uncreated, why not the universe?
If universe means cosmos including the possibility of a super nature in it. Then certainly the eternal thing is in that super nature. If it does not have a super nature in it, then I look at the laws of physics, and to matter and energy, and shake my head and think about it.
Frankly we don't know about the physics of God, so he could be an exception to this law we see. However the stuff we can see does not appear to be eternal, even if we assume that the second law of thermodynamics is just wrong...a pretty fancy assumption for somebody lead by science.
But we can have fun with the idea that regular matter and energy are eternal, and see what ridiculous implications we can draw.
Imagine that the big bang has happened an infinite number of times. And that each time the results are non-deterministic (which appears to be the nature of matter and energy per current state of physics).
Well, then because of the non determinate infinite sequence, every possible event physically possible must have happened already an infinite number of times!
What fun! Certainly pink horses with horns in their forehead must have evolved on some iterations! It must have happened an infinite number of times! And thus there must be an infinite number of invisible pink unicorns.
And just think, on some iterations there must have been some little folks with pointed ears and elven wings...but with tails. In some cases marvelous tails with some remarkable traits...any that were possible on some iterations.
Thus on such a view, fairy tails must be real!
Not only do you have angels...in infinite number...you have all creatures possible both in and out of mythology.
Of coarse, I think it more sensible to think of the thing beyond the beginning of the big bang as not just more of the same into eternity...but then, I'm at least as smart as a 4 year old.