First, that's assuming there was a big bang, not that I entirely disagree with it.
Well, there is lots of evidence for the Big Bamg, so it's not an assumption but rather a conclusion based on the evidence.
Second, I don't understand what you said by time losing meaning as we approach the big bang.
I believe you don't. But as I'm sure one of our cosmologists will explain to you, even time itself as well as all of our laws of physics just don't seem to make sense or apply as we get close to the instant of teh BB. In addition, terms like "before the Big Bang" definite don't have any meaning within the knowledge we have so far.
As for God, as I stated, I feel he's not made of any matter thus he's not affected by time but actually controls it.
That's fine. I also believe that. But it's also something where there is NO evidence either for or against and so has no place in any scientific discussion. It's just empty words.
When we study the universe we use certain laws that everyone accepts as fact to determine age, composition, size, temperature etc.
Well, actually we hold them as tentatively proved, as the best explanation we've had so far.
Using those same laws I just can't accept an infinate anything consisting of matter.
Fine. But again, incredulity has nothing to do with science or knowledge.
Aslan is not a Tame Lion