I would contend that the problem most people have with religion is based on the actions of humans rather than God.
Humans, for example, have squandered the message that Jesus left us 2,000 years ago. The only message he had for us was for us to love each other. That's it. Nothing more, but also, importantly, nothing less.
But humans twisted things around and created an awful religion around it called Christianity. I say that while happily acknowledging my own Christianity, but not as evangelicals or Catholics preach it.
I suspect adherents to other religions can point out ways their clerics have ruined theirs, too.
My belief in God comes from the simple fact that there exists inside of me a sense of right or wrong, and that sense expresses itself whenever I act on something.
I can choose to ignore it, but it is still there, and if the act is malevolent enough, it claws at me until I pray and ask for help reconciling it.
That the shame and guilt go away after prayer is the greatest proof of God I'll ever need. I don't need to see God. I feel God inside me every moment of my existence.