In the New Testament, the word most often translated “sexual immorality” is porneia πορνεία. This word is also translated as “whoredom,” “fornication,” and “idolatry.” It means “a surrendering of sexual purity,” and it is primarily used of premarital sexual relations. From this Greek word we get the English word pornography, stemming from the concept of “selling off.” Sexual immorality is the “selling off” of sexual purity and involves any type of sexual expression outside the boundaries of a biblically defined marriage relationship (Matthew 19:4–5).