Jesus shows us that the 6th commandment refers to more than just adultery when he said:
“You have heard that it was said, ‘You shall not commit adultery.’ But I say to you, everyone who looks at a woman with lust has already committed adultery with her in his heart.
DISCLAIMER: Catholic Answers has turned over the archive to Catholic-Questions.org and no longer owns, manages, or moderates the forums. For additional apologetics resources please visit www.catholic.com.