The universe as we know it had a beginning. It is constantly expanding and because of entropy, losing usable energy. Scientists have done math and came up with the big bang theory.
Given this, something must have already existed, that is unless you believe something can come from nothing, which is contradictory to the universe as we know it, and all of science. You think it's funny that God can be eternal, having always existed, or have come from nothing, but find it perfectly reasonable that the universe, having been proven to have a beginning, always existed or came from nothing.
Your whole post sounds a little... arrogant. You should remember that despite all the knowledge we have because of science, like the brain, subatomic particles, and the grand scale of the universe, we still hardly understand the full extent of it all.