Traditionally, in Judaism, Christianity and Islam, God has been an entity who looks like a man with a grey or white beard, lives in the sky and intervenes personally in the lives of people. The Greek god Zeus bears a lot of resemblances to the Abrahamic capital-G God. There's just one letter's difference between "Zeus" and "Deus," Greek for "God."
Today, most Jews, Christians and Muslims believe in a God who differs to a lesser or greater degree from the bearded man in the sky. Sometimes to such a great degree that, instead of "God," they could call it something else, like "physics" or "love" or "gravity."
So why do they still call it "God"? (Lucretius was posing the very same question to pagans almost 2100 years ago.) Nietzsche may have found the answer: he declared, in his book Der Antichrist, in the 52nd chapter:
"»Glaube« heißt Nicht-wissen-wollen, was wahr ist." ("Religious belief means not wanting to know what is true.")
They don't seem to want to know that not very long ago at all, when members of their religions said "God," they meant an omnipotent bearded man in the sky, and not physics or love or gravity. They seem to want to pretend that the bearded man in the sky was always a symbol, of -- something. Something other than an actual omnipotent bearded man who lived in the sky.
It's difficult to talk sense with people who don't want to make sense.
Nothing I've said in this post is a secret, or hard to understand. But many people, maybe most people on Earth, don't want to understand anything of the sort. Some of these people who don't want to understand such things, things which only become clearer and clearer with the passage of time, are intelligent enough that they have to study theology full-time just to keep themselves confused.