These types of arguments from theists are some of the worst ones there are.
Look, Godexists. I think everyone in their right mind would be willing to acknowledge the possibility that a supernatural force gave birth to our universe. Given the massive lack of evidence to back up that theory, is the supernatural theory the most plausible one? No. Not even close. Why? Because the only evidence we can currently gather in any way, shape or form comes from THIS universe. So you must first decide whether or not you consider what we find inside THIS universe to be a representative sample of what may exist outside of this universe. If you say, "No, the evidence within this universe is not representative of what exists outside of it", then the entire process is just a guessing game. If you say, "This universe is the only universe there is," then again, you are forced into a guessing game. BUT, if you say that you are willing to look at evidence from within this universe to determine the makeup of what exists outside this universe, then you are forced to first assume that what exists outside this universe is not supernatural. Because what science has discovered is that this universe appears to work in very natural ways. No hand of God is necessary to explain anything anymore.
If you are looking for alternate possibilities as to how our universe got it's start, I can give you a couple. One possibility is that our universe is one of many in a sea of universes, and at one point in time, 2 universes collided to form this one. Another possibility is that our universe is the ejected material from a giant black hole. Another possibility is that our universe is nothing but a single cell from a giant organism that resides in a universe which is also just a single cell from an even more giant organism and so on, and so on. All of those are more likely scenarios than the Christian God theory for one simple reason. They are natural explanations... the same type we use to explain things here in this universe. And if you decide to refute any of those theories with scientific inquiry, then you must apply that same level of scientific scrutiny to your Christian God theory and accept that a massive lack of verifiable evidence makes that theory an unlikely candidate for the first place prize.
The bottom line is this... There is no reason to accept the notion that the Christian God created everything. None. Zero. Zilch. It's a guess. And a really bad one. Any and all supernatural explanations are just examples of antique thinking. It's the same type of thinking that ancient man used when they couldn't understand thunder or lightning. "Gee, I don't know where those flashes in the sky are coming from, so I'm going to assume there's a magic sky man up there doing it." This is the same thing you are doing, only with a more modern topic. "Gee, I don't know how the universe got it's start, so I'm going to assume there's a magic sky man who did it." Science has pushed God into that realm by consistently discovering how the world REALLY works. We don't say God created lightning anymore because it's not a good explanation. Why do you think it's a good explanation for the beginning of the universe? Just because science hasn't figured it out yet? Please... that's just nonsense.
And even if you find some sort of evidence that the universe was created by a supernatural force, every bit of work is still ahead of you in determining what force it was. If you honestly think the Christian version of things would get some sort of preferential treatment in that respect, then I don't know what to say to you. I could just call you arrogant and egotistical, but those would be understatements.
FYI, God isn't real. Bank on it. The whole thing is fake. Don't take it personally; there's a whole bunch of people who buy into the foolishness just like you do.