In 1976, David proposed an unprecedented corollary to the Law of Love: He contended that, in certain circumstances, it would be acceptable for a Christian to have sexual relations with someone in an effort to demonstrate a tangible manifestation of God's Love, thereby helping them to come to a saving knowledge of Jesus Christ. This doctrine became known as Flirty Fishing," a term that David adapted from Jesus' admonition to His disciples to "follow Me, and I will make you fishers of men" . It was practiced by many Family members until 1987, when it was discontinued.
In presenting this new approach to soul-saving, David reasoned with his followers:
Do you really believe that “to the pure all things are pure” and that “all things are lawful unto you”?
What better way to show them the Love of God than to do your best to supply their desperately hungry needs for love, fellowship, companionship, mental and spiritual communication, and physical needs such as food, clothing, shelter, warmth, affection, a tender loving kiss, a soft warm embrace, the healing touch of your loving hands, the comforting feeling of your body next to theirs—and yes, even sex if need be! 
There's no amount of love that could possibly be illegitimate to try to win a soul! There's no sin in love to begin with, and there's no “sin” so great that God would condemn you for it when it's done in love, ... because when it's love it can't be sin. 
Any price is not too big to pay to save a soul! ... Jesus gave His life, and we should be willing to give ours. 
- See more on the history and theology of FFing or Flirty Fishing.
- "King Arthur's Nights, Chapter 1," ML #501, 1976.
- "Their Last Resort," ML #1985, 1981.
- "Solitaire," ML #1064, 1980.