If sexuality is good, why do we say that "lust," "impure thoughts," etc., are evil? In the words of Ferder and Heagle (1997):
Sexual feelings, desires, and images originate as spontaneous expressions of our growth toward relational maturity. Like other human needs, such as hunger, thirst, and security, they are in themselves good, or at least ethically neutral. It is our attitude toward them—the manner in which we consciously approach them—that gives them moral 'weight' or value. The sin of gluttony does not mean that food or hunger is evil, nor does greed imply that having material possessions is wrong.