Well actually, modern science does not say anything about time being finite, as far as I'm aware, only that the big bang happened at a defined point, and that it is considered the start of our universe. Of course, nobody knows what existed before that, but personally I'm interested in the fact that since the very first nanosecond of the big bang, there has been a fixed amount of mass/energy in the universe - never increasing or decreasing. So either existence has always been there in some form, possibly with the oscillating universe idea you mentioned, or that that energy/mass was created by a divine creator, to start things off in the first place.
It's something we can't possible know and never will know, I just find it interesting.
And yeah, I think I understand you now - if we talk about anything outside of what we think of as our universe, whether that is in time or space or any other dimensions that might exist, then you'd call that multiverse. And by that definition, I'd broadly agree that it is by far the least likely. But as I said, it still doesn't make it impossible, and so still can't be written off.