Arguments between atheists and theists about the existence of God are stupid. Whether God exists largely depends on one's definition of God. If you define God as the flying spaghetti monster then God doesn't exist for anyone. If you define God as the universe (as pantheists do) then God exists for almost everyone. If you define God as the Trinity then God only exists for Christians. So it all depends on the definition of God.
I define God as the aggregate forces of nature, both known forces and unknown forces. If you believe in science then you believe in my God. I explained the idea more in my old post God for Atheists.
If this issue is semantic then does it matter? Yes, it matters a lot. How you label yourself affects how others view you. If you call yourself atheist then you are identifying with evil morons (modern atheists), and this is how others will view you. But if define God as something that you believe in, then you can call yourself a theist and that is how you will be viewed.
But beyond this, you can use your newly defined concept of God to help shape your thinking. So this new semantic tool will influence how you think and how you behave in the future. In my case I concluded that the Old Testament is the best book for me to follow. And I concluded that I should attend religious service regularly and pray daily. I will explain these in separate posts.
If any decent person reading this isn't convinced to be a theist, please tell me why.
In addition to this, I think it is too complicated to think in terms of the forces of nature, so it helps to personify them as God. Similarly, it can be helpful to explain current events in terms of conspiracy theories, even if there is no conspiracy and it is all just market forces at work.
I define God as something that has personal authority over morality, which is why it doesn't exist.
If you take your garden-variety sci-fi evil-entity-pretending-to-be-God, which quality does it lack that makes it not actually God? Why do the characters in any one of these tropes reject it?
Is it a matter of power? If you took an evil, depraved Goa'uld symbiont and made it omnipotent, would it be God then? Of course not, Jack O'Neill would rightly answer.
Well, what if it created the universe? A difficult question, but I still don't think you would get an answer of yes from any reasonable person. It's still an evil being. It kills people for its own amusement. It commits genocide on a whim. It's supremely selfish to the point of being rightly classed as a psychopath. It turns people into pillars of salt because they look in the wrong direct-
I was talking about evil sci-fi entities. My bad.
My point is, we live in a universe where we have defined objective morality. Killing is wrong. Stealing is wrong. That's true no matter who says otherwise.
But God defines and dictates morality. So if God said murder was right, it would be.
But murder is wrong by definition.
So my answer to whether God exists is no by definition.
That thing in the Bible might exist, I don't care. It might be able to send me to Hell. I don't care. It might have created the universe. I don't care. It might be all-powerful. I don't care.
My answer to that entity is garden variety evil entity pretending to be God, and I feel I have derived this answer from a morality everyone can agree on.