You haven't proved this statement yet. You've been challenged on it before, but you always avoid it.
Proof?
Also, you assume that things without a beginning DON'T need a cause. Proof?
It's more like this, there are two options for the universe:
1. There is an actually infinite series of causes
2. There is an uncaused cause at the back of everything.
The only real question is which makes more sense since we may never be able to scientifically distinguish between the two.Now the uncaused cause wouldn't necessarily be God, but it could be. Or you could have an actually infinite series of causes, which I don't think makes any sense. But other people disagree.
Every phenomena we thought didn't have a cause turned out to have one. There are still phenomena we don't fully understand. We don't know about a cause of the Big Bang, that doesn't mean there isn't one or prove that it's God.
But I don't think the idea of an uncaused cause is irrational, or if it is it's no more irrational than an infinite series of causes. And God could still exist and have a cause of some kind. That means arguing God has to have a cause is a bit pointless.