I'm afraid I don't know any sure-fire solution. But I can at the very least offer my condolences and say that's you're not alone.
I'm in a very similar boat. I suffered no abuse of any kind growing up, but I understand how it feels to have the concept of sex be revolting and for masturbation to produce profound feelings for guilt or much worse. Especially when fantasies are involved.

I would highly advise you to talk to your therapist about this. If you really are too uncomfortable with the one you're currently seeing to bring the subject up, then try to visit a few others in your area to try and find one that works well for you.
I'm currently in therapy almost exclusively for this very reason. And I can tell you that talking about it and working through it with a therapist, while certainly more than a little uncomfortable, can do you a world of good.
My own is in fact currently debating on if should I start taking medication for OCD in order to control the compulsion and gradually diminish my sex drive as a kind of bonus side-effect.

I don't recommend you start taking meds as you're first step however. As I said, talk to a therapist. You say you want to change for personal and religious reasons and in order to move forward towards your goal, you will need to come to a better understanding of your own motivations.
I too have been able to cut down on my masturbation significantly but I understand how that's not enough.