I understand that; however, that really only makes any case for the existence of the universe as we know it, and not for the state of everything before the known universe or other than the known universe, which is pretty important to the discussion of creation/infinity.
i.e., just because the Big Bang created this space time, doesn't mean that spacetime didn't simultaneously exist elsewhere. In such a case, time is a little more "absolute" than the relativity we associate with it today (but only a little).
You're looking at it the wrong way, imo.
Firstly, you are changing the very nature of spacetime here. Spacetime is a relationship between objects in OUR universe. Even should other universes exist, the spacetime of those would be fundamentally separate from our own. Why? Because spacetime is the fabric of our universe--it makes no sense to hold that there are two universes that share spacetime, because those would just be the same universe. If spacetime is shared between them, then we have just arbitrarily drawn a line between the two and called one our universe and the other "Universe 2." That's nothing special, and it isn't multiverse theory.
Furthermore, the very way you are talking about these things is worrisome. You speak about spacetime "simultaneously" existing in two places. That's a temporal relation. For that to be the case, there would need to be ANOTHER layer of spacetime that encompasses those two universes. And we run into the same problem as before--it makes no sense for two universes to be connected by time.
Multiverse theory is fine (and there are plenty of physicists that believe it, though none have any real reason for doing so, afaik). But to hold that two universes exist in temporal relation to themselves makes no sense--it's an empty sentence without meaning. But, the thing is, beyond philosophical questions, multiverse theory is useless. By definition of what a universe is, it HAS TO BE completely separate from other universes. Even should multiple universes exist, if they were connected in any way they wouldn't be universes--they'd just be parts of one big universe. And that's not multiverse theory. It's just... weird.
What it sounds like to me is that you want to hold that there are multiple universes, and time progresses equally across all of them? That's just not compatible with current physical theories, where time is an intrinsic quality of this universe, at all. They could be wrong I suppose... but you really have no reason whatsoever for believing that to be the case (rather, you have every reason to believe they ARE correct).
When dealing with the difference between the infinite and the finite there is nothing that we (being in the finite) can do on our own that can truly measure the infinite. We can see that it is there and prattle about it (apparently)
Being that there are finite things in existence, which indeed implies space/time, and as such implies a beginning; so within the framework of the concept of where the finite universe came from is one thing entirely separate from trying to debate about the nature of the infinite.
Of COURSE that which is Infinite HAS NO BEGINNING; so the WHY do people love to ask Who created God?
People go at SUCH sad lengths to try to disprove the remote possibility of a sentient creator. If you believe that we in flesh are sentient in electro-chemical impulses then even that cannot discount the notion of a possible sentience existent within the nooks and crannies that exist between the finite and the infinite.
I find it odd that you are claiming humans to be finite creatures, considering you're religious. I definitely think we are finite, and I don't believe in souls at all. But a person who believes he is a soul, rather than a body, should believe he's infinite, no?
And no, there's nothing about spacetime that implies a "beginning." Not in the way you want it, at least. Spacetime regards the relationship of entities within the cosmos. Before (atemporally) spacetime existed, the energy that would later form matter still did. And the laws of physics as we know them demand that it HAD to exist. They don't know what form it existed, no. And they theorize that the universe doesn't have enough mass to be constantly cycling through Big Bangs and Big Crunches. But it's a basic fact about the universe that energy is always conserved.
Furthermore, people only go to great lengths to disprove the existence of God because pricks like you keep trying to shove your misguided, illogical beliefs down our throats. We ENJOY showing you how stupid you are, because you ANNOY us when you try to convert us.
Plus, if we are soulless creatures (that is to say, creatures such that we are only flesh and blood) then it doesn't really matter if there is a god or not is there. You're going to cease to exist when you die, just like the rest of us. ****, in that case, I'd be HAPPIER believing there wasn't a God (compared to believing there was and cursing him for being such a ****).
Finally, "nooks and crannies that exist between the finite and the infinite" doesn't mean anything.