Homosexuality is punishment for sinners? Huh. I've never heard that one. Who told you that?
And as far as masturbation or anything like that goes (same goes for overeating, neglecting prayer, etc.), the problem is that we are supposed to struggle against the passions, not give into them. It's certainly much easier said than done (one of the many reasons to take St. Paul's advice that it is better to be married than to burn with passion), but then so is everything. You're not going to escape that by leaving Christianity. Life will still be full of things that are hard to do but still must be done for various reasons.
I find it very interesting that Christianity in your view is all about a mechanism of control of the person, when internally it teaches the control over external forces (e.g., the passions and lusts of the world). I think it was St. Augustine of Hippo in his City of God who made the point that a slave may be comparatively more free than his rich master if the master is more bound by what controls him. This is even more laid bare in the passion of Christ, in which He most definitely suffered and died but throughout which nothing controlled Him. As He Himself said of His life "I lay it down of my own accord; no one takes it from me."
This is what it is really all about: that we are freed of the control that the world would put on us anyway, regardless of whether we call ourselves Christians or not. Christians are just in theory supposed to be better at recognizing it and fighting against it, through fasting, prayer, self-denial, etc.
Anyway, just some thoughts. May God bless you and guide you no matter where you go.