Keep in mind that the depth of your perception is (from my beliefs) or maybe (from anyone else's) extremely limited. The way I see it, the cosmos can be compared to a virtual machine running inside of a real machine. You might be a process inside of that virtual machine and have no idea where you really exist relative to the other processes and parent machines above you. If we think of God as the "programmer" over this machine, then we can imagine quite simply that at one point, He spawned a virtual machine (this universe) and subsequently initiated some processes inside of that machine to act as life in the universe. (I actually like to think of people as external clients connected to the virtual machine, but that's beyond the scope of what I'm trying to say right now.)

At any rate, being God, He could have initiated this "machine" with its "hardware" set to any state he chose. Light projected from stars billions of light years away would take multiple millennium to reach Earth, but only if He let time play out like that -- and the Bible points out quite clearly that this was not the case. Being in complete control of this machine, He could certainly have "thought" the setting of the universe into existence at whatever state He chose; and being a sub-process inside of this machine, of course there's no way a simple being such as yourself could see whether this is the case or not! (what's interesting about that last statement is that, if we really have no clue where we come from, how does an idea as far-fetched as "God" really come into existence? hint: it's an implanted thought.)

So if you think about the universe as nothing more than the projection of rational thought (just like a computer), in this case that of God himself, than the idea of a universe that once was not -- and then was -- and soon will not be -- makes perfect sense.

This all still begs the question, however -- where did God himself come from? Scientifically speaking, no one knows. The Bible says that He has always existed, and I am satisfied with that. And how can you blame or scoff at me for saying such a thing -- there are multiple theories today that suggest that the physical universe was never created, but has always existed in one way or another. So how is the idea of an omnipresent God any different?