Friends with benefits is a sin because it goes against the teachings of the major world religions, which all have strict guidelines regarding sexual relationships. These religions promote the idea of monogamy, or lifetime commitment between two people, as a sacred practice. Having a “friends with benefits” relationship is essentially making a commitment to one another without making a true, committed bond. It also goes against the moral teachings of these religions, which promote the importance of treating our partners with respect and nurturing the relationship. Having a “friends with benefits” relationship sends the wrong message about the importance of commitment and respect in relationships.