Just speaking technically;
I have heard Christian clergy state the following, and this is damn near word for word because I was so shocked by it that I asked him to repeat it and wrote it down.
He said that masturbation was a form of the sin of murder, and equally serious.
Here was the reasoning behind it, if you can dignify such drivel with the term reasoning.
Every sperm is a potential human life. Therefore, any sexual activity which 'wastes' sperm by putting in a place where it has no chance of fertilizing an egg and producing a baby is a form of abortion, which they consider to be murder. Therefore, not only masturbation, but fellatio to ejaculation, sodomy, bestiality, frottage, are all forms of murder, as is the use of any form of contraception that actually works, including condoms.
Interestingly, there is one very special circumstance under which masturbation is actually not a sin by those standards; when it is done to create a deposit in a sperm bank! That still keeps the chance of making a baby open, and therefore it is not a sin.
Wild. So jerking off equals murder. Damn, I'm a serial killer! Ahhhhhgggghhhhh!
I better go turn myself in.
😛