You don't believe in Zeus and thousands of other once up-front-and-centre deities. I don't believe in God and thousands of other once up-front-and-centre deities (including Zeus). The actual evidence (or lack thereof) for either and the principle involved are actually exactly the same.
Had you been born 10,000 years ago you'd be singing the praises as a convinced True Believer in one or more of those thousands of other once up-front-and-centre deities. You'd of never heard of Yahweh or Jesus or Allah or Mohammad.
As noted above, throughout recorded history, even up through and including the present, there have been thousands of other once mutually exclusive up-front-and-centre religious deities, as well as currently being but still mutually exclusive up-front-and-centre religious deities. The question obviously arises, why is your one religion and your one deity (assuming you are a monotheist) the be-all-and-end-all of absolute truth? You got competition my friend!
There is no proof or even evidence for any monotheistic deity's existence. If there was then no debate on the question would need to be entered into since we'd all be unified as True Believers in that one be-all-and-end-all of absolute theological truth.
One cannot argue the existence of God (specifically) from morality since God (of the Old Testament) is the most immoral being ever conceived of in any existing literature. "God" and the word "love" or "mercy" or "compassion" just cannot be used in the same sentence.
There's no need to postulate the existence of God in order to explain the existence of life, the Universe and everything since the existence of life, the Universe and everything can be easily accounted for without resorting to any involvement by a supernatural deity.
There's no independent historical or archaeological evidence that any of the major events ever happened, like the Flood or the Exodus or the Battle of Jericho. Further, there's no independent historical or archaeological evidence that any of the major Biblical characters ever existed, like Abraham or Noah or Moses or Joshua or Jonah. To top things all off, the Bible is absolutely full of inconsistencies, contradictions and other logical nonsense.
Prayers and miracles have been debunked. An obvious example is that God can apparently cure all manner of cancers but seems utterly unable to regrow the limbs of amputees. Are the latter less worthy of God's miraculous abilities. Surely both groups of people pray. More to the point, if God is all-powerful, wouldn't it have been better to have ensured that said cancers never got a start in the first place. Prevention is always a better option than cure.
Any personal spiritual experience of your personal God is just that - personal, and therefore subjective and therefore lacks persuasive evidence to convince anyone else. People personally experience and report all manner of strange things. Perhaps brain chemistry and mental states tend to be a more reasonable explanation for 'spiritual' experiences and visions.
When it comes to theologies, religions and deities, the majority doesn't rule. For example, the actual existence of God isn't up to a democratic vote no matter how many True Believers exist. Even if a billion people believe a foolish thing it's still a foolish thing.
The proof of the Christianity pudding would be in the End Times eating. Jesus said that the End Times would happen within the lifetime of those hearing his words. His intervention (i.e. – Second Coming) should have happened within the lifetime of individuals that Jesus himself addressed. Oops! Be that as it may, well-meaning educated theologians and others (often not quite so well educated) have been saying "Jesus will intervene in the near future" for hundreds and hundreds and hundreds of years now. If I had a $5 bill for each and every time someone said "Jesus will return in the near future" I'd make Bill Gates look poor! The "near future" never, Never, NEVER seems to arrive. Though I of course won't be around to see it and collect, I'd bet the family farm that our human descendants 500, even 5000 years from now will be saying "Jesus will return in the near future". Don't hold your breath. The Bible was written by humans for humans; ditto every other religious text - unless one can of course produce a certain set of stone tablets but for some mysterious reason, they've gone missing!
The origins of religion have been adequately explained without the need to reference God (or any other deity / deities). Religions collectively have their roots in the purely human need to explain the unexplainable (agency); the desire for an afterlife which you are unable to provide for on your own behalf; and the uniquely human habit of being a habitual storyteller. In fact nearly every time you dream you are making up a fictional story!