Claim. God deliberately interchanged ownership of the sexual organs — a man’s belongs to his wife, a woman’s to her husband — so that neither could ever use them alone or together with another partner.
Elaboration. §4.2 develops what SMM treats as a wisdom-of-God argument: ownership exchange is what guarantees fidelity. “Man’s treasure is not owned by him. It is owned by the woman, and her treasure belongs to him. In short, ownership has been exchanged… Therefore one cannot do as one likes with their sexual organs” (4.2. The owners of the sexual organs were interchanged, 162-50, 1987.3.22). The corollary: marriage is the act of finding one’s true owner. “Through marriage men and women are to find the owners of their sexual organs” (ibid). The wider rule: “Thinking that your sexual organ belongs to you is a sin. It is a grave sin for women to think that their sexual organs belong to them” (ibid, 141-172, 1986.2.21). The implication is that adultery, free sex, and homosexual practice are not just morally wrong but ontologically incoherent — they treat as one’s own what God’s design made another’s, structurally impossible.
See also. csg-spouses-own-each-others-love-organs, csg-conjugal-love-is-holy-and-exclusive