Is masturbation a mortal sin?
Yes, it’s a mortal sin. The act separates the procreative gift from the marriage relationship, so even if you’re married, mutual masturbation is not permitted. There is some biblical reference to this in Matthew 5:27. Here, Jesus says that whoever looks lustfully at a woman has already committed adultery in his heart. Masturbation is indeed a fantasy, where a person commits a sexual act in the mind. One might argue that it’s possible to commit the physical act, without thinking of a woman. I would argue – hogwash. But either way, it is clearly defined as a mortal sin in the catechism in paragraph 2352.
