In general terms, any married person who has sexual intercourse with someone other than his/her spouse, or any unmarried person who has sexual intercourse with a married person, commits adultery. According to the words of Jesus: "But I say to you that whoever looks at a woman to lust for her has already committed adultery with her in his heart" (Matthew 5: 28), "adultery of the heart" can occur despite an outwardly blameless conduct of life. This commandment is not only violated by committing the actual act of adultery, but already when it is played out in thought (Mark 7: 20-23).

See also