"I believe in God," you insist. Sure, and the god to whom you refer both expects and allows you to live pretty close to how you want. That's the god you believe in. Actual God doesn't count that belief as believing in God, because it isn't Him, actual Him, Whom you are believing in.
What I'm writing about, the Apostle Paul describes in Romans 1:25, 26, and 28, which together read:
25 Who changed the truth of God into a lie, and worshipped and served the creature more than the Creator, who is blessed for ever. Amen. 26 For this cause God gave them up unto vile affections. . . . 28 And even as they did not like to retain God in their knowledge, God gave them over to a reprobate mind, to do those things which are not convenient.People change the truth of God into a lie. The idea of "the truth of God" in this context is "the truth about God." They reject the truth about God for a lie about God. They call their god, God, but in fact they serve the creature. Their god functions within their own parameters.
Verse 28 expands upon verse 25 by explaining that they "did not like to retain God in their knowledge." "Did not like to retain" is literally that "they approved not to have God in their knowledge." The second half of 25 is a play on words. "Approved not" is ouk dokimazo and "reprobate" is adokimos, both the same root words. Their minds trash God, and their minds become the judgment of God itself. Men can't think straight when the one and true God isn't accepted in their thoughts. Their minds become what their minds do. Their minds trash God and their minds become trash. The judgment is a built-in consequence.
The chief alternative god to actual God, that I see today in the world, is what I call the goodymeister. He's a kind of living vending machine. He's perfect for men walking after their own lusts, who don't want a boss. Knowing he is who men want as god, churches offer him as god to their people. He does not form in their imagination mainly through a doctrinal statement, but by the style and substance of the preaching and the worship. They give him, this goodymeister god, what they like, what they would want if they were him. His adherents would gladly serve him, because he wants the same things they do.