No, I was not there, nor were you, which means you cannot say for sure there was a Big Bang, can you?<quoted text>
Could you clarify premise 3?
"Before the beginning of the universe, there was no universe."
I'm going to take the cheap shot Creationist rebuttal here and ask "Were you there?"
As far as I know, no scientist has put for a testable hypothesis for what was before the Big Bang.
There is the multi-verse idea but doesn't that kill the "we are a special snowflake universe" like Earth is the center of all creation?
Since the universe is everything that exists, and since it had a beginning, therefore, before that beginning it did not exist, did it? And since everything that exists did not exist, that means nothing existed and there was nothing.
Since something never comes from nothing by any natural cause, therefore the cause of the universe, which came from nothing, must be supernatural.