(Gaithersburg, Maryland-AP) -- Christian author and pastor Joshua Harris says lust is a lie that robs people of their ability to enjoy the pleasure that God meant for partners in marriage. The author of "I Kissed Dating Goodbye" and "Boy Meets Girl" has written a new book titled "Not Even a Hint: Guarding Your Heart Against Lust." He cites C.S. Lewis's illustration of lust as a lying lizard that teases and gnaws at a ghostly man -- until that man lets God kill the lust. Only then is the lizard transformed into a stallion of fulfilled desire in a man who's become real. The 29-year-old Harris says purity is strength -- and leads to the joy of giving love in a committed relationship instead of the emptiness of taking momentary pleasures. Joshua Harris is executive pastor of the three-thousand-member Covenant Life Church in Gaithersburg, Maryland.