Christians, what is your VERY BEST arguments for the existence of God?

[Tiberius]

someone said the big bang is an event in the history of the universe not how the universe came into being. isnt this akin to someone saying my birth is an event that took place in my lifetime not how i came into being.

You could say that. The point is that the universe existed as a singularity, and then the Big Bang was the expansion of that singularity. Space and time expanded, forming the universe. The Big Bang theory does not say how the singularity got there, nor what happened "before" the Big Bang, or even if there was a "before" (since if time started at the Big Bang, there was no "before").