It’s pretty simple. You have two basic premises when you try to get to the first cause (if there even is one)
1- The energy that makes up the universe is eternal
2- The universe was created by a god. That god is eternal.
Its pretty obvious the first is the simpler answer. The principal of Occam’s Razor says that all evidence being equal, the simpler one is probably right.
The only thing you really do by adding a god is delay the conclusion that something is eternal a step. It doesn’t actually answer anything. It doesn’t change the outcome. It only adds an unnecessary step. And the worst part is that step has no evidence to support it.
Does everything even have a cause? Nope. Talk to anyone who works in quantum mechanics and you will find out. When you look at the radioactive decay of a single atom there is no way to predict when it will break down because there is nothing that causes it to break. So in this case, insisting that there even is a cause is complicating the thing when there is no evidence it even has to.
If you don’t know the cause, does that mean you can’t know that the thing happened? I bet 99% of you don’t have a clue what causes this website to display in your browser. But you do know that it does. We know the Big Bang happened. It made several predictions, and the Cosmic Background Radiation alone proves it. I mean we can even map out the energy of it. There really is no wiggle room on rather it happened. Do we know how? Nope. But that doesn’t mean it didn’t.