Evolution has clearly shown us there is no need for a god to take simple life to complex life and 'fill the earth' with life. Studies of the origin of life are still lacking as it seems difficult to make nonliving matter cross over. But science will figure that out one day, perhaps millenniumso from now when it can be observed on a lifeless world about to have lightning strike it's primordial soup (or volcanic action or whatever ).
As far as the big bang, some of the people in science are strutting like a peacock in saying they got it all figured out. That's a shame because they don't. But I am satisfied that their various theories are causing much more investigation than stopping at "God did it" ever will. They have shown that a god isn't the needed ingredient.
keep in mind that there really is no such thing as eternity to the past of the universe. Time was meaningless until it was started by the big bang. So our limited minds are thinking of what we perceive and we come up short. I find it easier to understand matter-energy and antimatter-energy coming into existense by scientific explanations than I do by the "God did it" answer that leads us to a dead end.
But since the mind is limited and finds this so difficult, I usually don't argue the very first cause. Instead, I accept the proofs that the gods of mankind's understanding do not exist and I say that if any supernatural power can influence our lives (or afterlives) then he/she/it is free to reveal such to us in a clear way. Until then, we need to keep looking for answers that are on a path we can actually continue down.