Defining "Adultery in the Heart"

Jesus’ words, “You shall not commit adultery..., everyone who looks at a woman lustfully has already committed adultery with her in his heart” are addressed to all men and women living in our fallen state burdened by the heritage of sin but redeemed by Christ. Although Jesus seems to be addressing himself only to men, he addresses himself to women as well. Both can commit adultery.

But what is adultery? What is adultery in the heart committed when a married man looks lustfully at a woman who is not his wife?

Viewed externally, adultery is a violation of the law of matrimonial exclu-siveness, a breach of the unity by which husband and wife become "one flesh." It is a violation of the exclusive unity of husband and wife. Externally, a married man commits adultery if he engages in a sexual union with a woman who is not his wife. The woman likewise commits adultery if she unites in this way with a man who is not her husband. In our usual way of understanding, adultery is an “act of the body,” an act manifested in the body, committed when someone actually and physically engages in a sexual act with another who is not his wife or her husband.

But Jesus, by talking about adultery committed in the heart, shifts the debate about adultery and about morality away from mere external actions to what goes on in a man’s heart. One can commit adultery “in the heart.” Adultery in the heart is an interior act. It is committed by the man when he looks at a woman lustfully. It concerns an inner desire directed, in this case, by the man toward a woman who is not his wife, with the intent of engaging in a sexual act with her. This inordinate desire is expressed by means of looking lustfully.