For a god existing the evidence is...
Plainly it's possible for any supernatural being, indeed any being you can think of, to exist as a concept or thing imagined. Superman, Voldemort, Mickey Mouse, all do this.
But if, as seems reasonable, there's a condition that God should have objective existence, in other words should be real, found in nature, not imaginary, then for the positive case it appears there's no evidence, and for the negative case it appears the evidence is extremely strong.
At the heart of this problem, as far as I can tell, is the absence of any coherent concept of what a real god is. Not through want of asking, I've never found a definition of God such that if we found a real candidate, we could determine whether it was God or not.
Without that, it seems to me that to speak of a real God is to have no coherent idea of what you're talking about.
And that this is indeed the case.
For a god not existing the evidence is...
1. As above.
2. The simple observation that God is never seen, never says, never does, is only known through tales from our fellow humans.
3. The observation that world behaves exactly as if God is / gods are ideas in individual brains, not real entities.
4. The wide-reaching failure of believers to agree on what supernatural beings exist, what they are, what they do, what they require, and so on, which is consistent with supernatural beings being artifacts of other aspects of human mentation rather than real entities.
5. The absence of any authenticated example of magic ('magic' being the alteration of reality independently of the rules of reality) ─ a necessity for concepts like miracles, souls, heaven and an afterlife.
6. Other reasons that will occur to me after I've posted this.