But I tell you that everyone who looks at a woman in order to desire her has already committed adultery with her in his heart.
In this passage Jesus deepens the meaning of the commandment “Do not commit adultery,” emphasizing that sin is not only in a physical act. He says that even the person who looks at a woman with lust has already committed the sin in his heart. This word shows that sin begins with thoughts and the condition of the heart. Jesus explains that the outward act is only the expression of sin, but the real sin is born within a person—in thoughts, desires, and emotions. He teaches that keeping purity before God requires not only controlling behavior, but first of all purity of heart and thoughts. Thus, Jesus calls us to watch not only physical actions, but also the state of the heart, avoiding desires that can lead to sin, even if they do not become reality beyond thoughts.