How did I reach my conclusion? Observation, for one: there is no apparent evidence of a deity, or at least not one who gives a damn. Science has poked holes into the Bible's timeline on the origin of the universe. Science can explain the origin of the universe more coherently than any theist. And Stephen Hawking, perhaps the most brilliant physicist in history, concluded that there need not be a god and, in his final analysis, that there even cannot be one:
https://www.livescience.com/63854-stephen-hawking-says-no-god.html
I used to believe in God when I was a child. And then I gave it some thought and concluded otherwise. And, as I said, the science supported that conclusion. Yes, there are some "scientists" who believe that there is a god, but the majority do not. I'll go with the majority.