When I mentioned this the other day I was asked "what word would you say instead?" Which highlights exactly the point I dont want to make. The word God is as good as any other. The word itself it not a problem. The danger is when we use that one world to mean different things.
God has a fairly sensible meaning. "Something which is worthy of worship". Generally an omniscient, omni-etc being which created the universe. The problem is when people try to argue about a different meaning of God as though it were the same. Sometimes this is the "no true Scotsman" fallacy, sometimes it's just downright word-magic.
The classic example is people who argue that there is a Church of England God who wants us to go to church on a Sunday and use the book of common prayer by using the cosmological or ontological argument. Now, as it happens both of those arguments are nonsense, but for the sake of argument let us assume they work. What you have proved if so is that a being either "that which no greater can be conceived" in the ontological case or "the uncaused first cause of all". Neither of these ideas contain the slightest reference to the Book of Common Prayer. To argue as though they're the same is just plain wrong.
Language is complex. We often use terms non-literally or non-exactly. We talk about an electron "trying to get to the lowest energy level" knowing damn well that of course the electron hasn't got desires or anything of the kind. The important thing is that it's clear what the metaphor means. In this case that the electron will tend to occupy the lowest energy level it can consistent with the exclusion principle etc etc. If you cant unpack things in this way then there's no point saying it. It's not real communication, it's just you saying words. What's not acceptable, what's not meaningful communication is:
"This book in my hand is the most perfect book in the world. It is a literal and perfectly true account of historical events. I base my beliefs and actions on the premise that the events contained in it are genuinely true."
"But this event mentioned here is clearly false."
"That's a metaphor."
To say that the book contains non-literal accounts is fine (so long as what those non-literal accounts mean is clear, which it isn't), but not if the literal accuracy of other parts of the book is something you rely on. Simply put, how do you know what's a metaphor and what's literal?
God is your father
Even given what I said about metaphor "God is your father" is a really bad example of the species. Because it gives a misleading idea of what the relationship between creator and created is. Same problem is implicit in the line "a smooth sea never made a skilled mariner". A loving father does need to be harsh so that his child can survive in the real world. Someone does need to expose a sailor to rough seas so they can survive in the real world.
But in no sense is this true of someone who creates the real world in question. A far better analogy, if we must use one, is to AI and programmer. The programmer can create the virtual world in which the AI is to live. There's nothing to limit what experiences this AI can have. So there's no compulsion on a loving programmer to expose the AI to harsh environments so it can survive in the "real world", there's no reason the AI ever needs to experience a scary world.
While I'm at it, see also the word certain, impossible etc. There are really really intelligent an well read theists, really really intelligent and well read atheists, really really intelligent and well read agnostics. So you can probably guess that at least someone has heard your argument, it's probably not as knock-down as you think it is. It's not a proof, it's just not.
Also while we're at it. A rather bizarre syllogism that people need to stop using. "You cant prove p" is not a proof that "not p", these are very very different statements.
I know you live in the West. I know it's sometimes easier to just stick to what you know and have experience of. But seriously. The God of Abraham is not the only god.
(Btw, as I use it, there is a difference between God and god, a god is a type of thing, God is the name of one such example, God is another word for Yahweh).
This comes up a lot in Pascal's wager type discussions. God or not God is too simple. Which god? The question is how many gods are there and what are they like?
Just a quick thing because this is something that offends me. Your religion and your holy book did not invent ethics. People do not need your religion to be moral. Please please dont be so arrogant as to think that you have unique access to moral truth. You just dont.