Although I am a believer I think that non-belief is a very reasonable and very defensible position
This sounds odd to an empiricist. You say that you have evidence of a god in the messages of a man. When I say that I believe something, I mean that I have compelling evidence to support that belief that any other critical thinker ought to find compelling as well if he can connect premises and evidence to conclusions via valid reasoning. Such people tend to agree on matters of fact, and when they don't, they have a common method to reconcile those differences and come together.
Belief isn't nearly as subjective as you depict. If I thought that the writings of Baha'u'llah were compelling evidence for a deity, I would expect most if not all critical thinkers to agree upon inspection of that evidence. And those who didn't share this method (dialectic), people such as creationists, who look at the evidence for evolution and don't see what it implies, I would not call reasonable or holding a defensible position.
It certainly is nice to hear this coming from an atheist and it is also rare, because most atheists think that theism is an untenable position, unreasonable and indefensible.
Most if not all critical thinkers agree that insufficiently supported belief is unjustified belief.
Certain strategies for justifying theism are well-reasoned. I've been surprised how defensible a position that theism can be when a few key concessions are made.
Abrahamic theism would do well to get rid of the tri-omni stuff. It would eliminate many paradoxes and contradictions with observed reality. No more trying to defend the existence of a deity in the face of suffering, or why it never manifests.
But it's still left with the problem of insufficiently supported belief, which is not well-reasoned, unless one is satisfied with comforting placebo rather than truth. This appears to be the case in most instances, although no in @Trailblazer 's case. We have a theist on RF who strongly advocates for skeptics to relax their standards and let this belief in, because it comforts him. I have explained to him that that is of no value to the person who has matured outside of religion and learned to accept that we may live in a godless universe and that there may be no afterlife. It may be reasonable to continue to be a theist if one has that need, but the belief still isn't reasonable even if holding it is.
Some arguments for theism are very well-reasoned, honest, and carefully constructed. John Hick put together an argument for the reasonableness of religious belief based on direct mystical experience being just as privileged than everyday experiences of ordinary phenomena. To Hick, a mystic is justified in taking the object of his/her mysticism to be real because that experience is no better or worse than the experience of looking out of a window and seeing a tree, or whatever
I wouldn't accept that argument. The mystical experience isn't evidence of anything except that the human brain can have these experiences, not that they refer to any actual referent outside of the mind. The experience of the tree allows one to make accurate predictions about reality that guesses about the significance of a mystical experience cannot. If one goes outside and runs as fast as he can at the object of his mystical experience and then again at the tree, there will be only one interaction with reality.
That may be enough for some to believe both exist outside of one's head, but I would suggest not for those adept at reasoning.