I don't buy the scientific reasoning that something is scientifically true because it fits within one theory which has not yet been contradicted (or improved) by another theory.
The scientifically correct reasoning would be that until the model (the theory) helps me doing something it is valid within that limited scope. But my limited model is not THE TRUTH. It is just a tool in my knowledge toolbox. And I can get a better tool tomorrow. I can, because it's a tool and not the "ultimate knowledge". It would be impossible to improve on that.
Saying that the universe is limited because human means do not "see" much beyond a certain (huge) distance and because it is (or appears to be) "expanding" does not sound scientific to me.
An "infinite" (whatever that means) number of universes could exists and expand, or contract, or play leapfrog with each other without us knowing or suspecting. Even if our "universe" were really expanding (not everybody agrees but that's another point) that doesn't mean it is the only universe or, for that matter, the only KIND of universe. There could be as many different universes as there are different animal species on Earth, and we would be discussing our universe just like a deep-see crab would think there is no universe without water.
What we call "void" could actually be filled with some sort of substance of which we do not even suspect the existence. And by the way, even if "void " actually exists and is "void", "void" exists so it is and if it is, is part of the infinite, although a void infinite. An infinite void could not be negated.
This kind of questions will never have and answer because human ability to study this kind of problems stops much before human ability to ask this kind of questions.
I have nothing against atheism and I guess I have been an atheist (or, rather, a sceptic, which is different) myself but I do find that some atheist scientists try to use science to forward their own prejudicial idea and paint it with scientific objectivity.
Honest scientists when confronted with this kind of questions just raise their hands and declare the insufficiency of scientific means to give any kind of answer.
Any other position is IMO motivated by meta-scientific prejudices.