Rachel Held Evans bemoans it:
Currently, evangelicals tend to force young adults, especially young women, into simplistic sexual categories. They are either “pure” or “impure,” “whole” or “damaged,” “virgins” or “sluts.” There does not seem to exist a vocabulary within evangelicalism with which to talk about men and women who are sexually active, but not promiscuous.
But like it or not, nearly every study you find shows that unmarried Christians are just as sexually active as unmarried non-Christians. … [I]f evangelicals feel that the word “slut” is the only appropriate one to use for a woman who is sexually active, then we have a real problem on our hands.
The Dish 