Answer
In the Bible, "adultery" is sexual activity between parties when at least one party is married. Fornication is sexual activity between unmarried people. However, sexual desire and fantasy are not equated to sexual activity on a one-to-one basis. For example, throughout the Song of Solomon, the Shulamite and her shepherd lover are not married, yet they fantasize about sexual activity with each other. As one instance out of many in the book, in Songs 7:7-8 the shepherd proclaims, among other things:
"Your stature is like that of the palm, and your breasts like clusters of fruit. I said, 'I will climb the palm tree; I will take hold of its fruit.'"
And part of the Shulamite's response is:
"Let us go early to the vineyards ... there I will give you my love... [A]t our door is every delicacy, both new and old, that I have stored up for you, my lover."
These fantasies are sexual in nature, yet the shepherd and the Shulamite are not condemned for having them. Rather, their love is exalted as pure, something to which others should aspire.
Now, it is worth qualifying these statements by saying that fantasizing about a sin is a sin. What I am talking about is fantasizing about legitimate sex, sexual fantasies that assume a marital relationship that legitimizes the sex within the context of the fantasy. Such fantasies are wrong if the one having them does not have a right hope of marrying the object of the fantasy.
On the other hand, nowhere does the Bible condemn sexual desire toward a person to whom you are not yet married but rightly hope to marry. In fact, in a number of places such sexual desire is recognized and affirmed (e.g., Deut. 21:11).
Matthew 5:27-28 is sometimes taken as a prohibition against sexual desire of all sorts for anyone to whom one is not married. However, the actual wording and context of these verses suggest that the desire is specifically evil. That is, the desire is to commit an act of adultery, not to commit an honorable act of love within the context of marriage. Jesus is basically saying, "It is not only a sin to commit adultery; it is also a sin to lust after adultery." But this is a far cry from saying that it is always a sin to have sexual longings for anyone to whom you are not yet married.
Answer by Ra McLaughlin
Ra McLaughlin is Vice President of Finance and Administration at Third Millennium Ministries.