Although I first asked, "Where did the universe come from?" and "Where did God come from?", when I was just a child, I never entertained the notion that the universe has always been here; despite, at one time, believing that God had always been here. When I realized that the two questions were interchangeable, it didn't seem so odd to think the universe had always been here.
I thought about that for awhile and realized that creation is an illusion. Nothing is ever created. Things just change form. It's called the First Law of Thermodynamics; the conservation of energy. We really are made from stardust. The universe itself existed as pure energy, in a singularity, before exploding into the immense cosmos that awes us at night. The universe transformed from energy to matter; Einstein's E=MC2.
I've always thought of the universe as the cosmos. But in fact, the cosmos is just one form of the universe. The universe also existed (and might again exist) as a singularity. In one form or another, the universe must always have existed -- if the First Law holds true in a singularity (which is something we don't know for sure).
We know the universe exists, so it must have always existed. It's truly eternal. But we don't know, in the same physical way, that God exists. If the universe is truly eternal, God (The Creator) never needed to exist: we already had a universe (singularity or cosmos). If we don't know God exists and the First Law suggests he never needed to exist, then why insist that he does?
When we watch TV, we know that man invented it as well as the videos it displays. We know no other animal invented any of it because the "creator" must be more complex and intelligent than the "created". If God created the universe, he would have to be more complex than the universe. As awesome and mysterious as the universe is, God would have to be even more so. What purpose does it serve to unnecessarily add this supernatural layer of complexity? Isn't trying to understand the natural universe enough?