CS Lewis on Sex in Marriage and Without

“The Christian idea of marriage is based on Christ’s words that a man and wife are to be regarded as a single organism….The male and female were made to be combined together in pairs, not simply on a sexual level, but totally combined. The monstrosity of sexual intercourse outside of marriage is that those who indulge in it are trying to isolate one kind of union (the sexual) from all the other kinds of union which were intended to go along with it and make up the total union. The Christian attitude does not mean that there is anything wrong about sexual pleasure, any more than about the pleasure of eating. It means that you must not isolate that pleasure and try to get it by itself, any more than you ought to try to get the pleasures of taste without swallowing and digesting, by chewing things and spitting them out again.”

CS Lewis, Mere Christianity