The following text is excerpted from a fascinating article by Walter Wink, printed with permission.  The full text is here

Judge for Yourselves

The crux of the matter, it seems to me, is simply that the Bible has no sexual ethic. There is no Biblical sex ethic. Instead, it exhibits a variety of sexual mores, some of which changed over the thousand year span of biblical history. Mores are unreflective customs accepted by a given community. Many of the practices that the Bible prohibits, we allow, and many that it allows, we prohibit. The Bible knows only a love ethic, which is constantly being brought to bear on whatever sexual mores are dominant in any given country, or culture, or period.

The very notion of a "sex ethic" reflects the materialism and splitness of modern life, in which we increasingly define our identity sexually. Sexuality cannot be separated off from the rest of life. No sex act is "ethical" in and of itself, without reference to the rest of a person's life, the patterns of the culture, the special circumstances faced, and the will of God. What we have are simply sexual mores, which change, sometimes with startling rapidity, creating bewildering dilemmas. Just within one lifetime we have witnessed the shift from the ideal of preserving one's virginity until marriage, to couples living together for several years before getting married. The response of many Christians is merely to long for the hypocrisies of an earlier era.

Our moral task, rather, is to apply Jesus' love ethic to whatever sexual mores are prevalent in a given culture. We might address younger teens, not with laws and commandments whose violation is a sin, but rather with the sad experiences of so many of our own children who find too much early sexual intimacy overwhelming, and who react by voluntary celibacy and even the refusal to date. We can offer reasons, not empty and unenforceable orders. We can challenge both gays and straights to question their behaviors in the light of love and the requirements of fidelity, honesty, responsibility, and genuine concern for the best interests of the other and of society as a whole. Christian morality, after all, is not a iron chastity belt for repressing urges, but a way of expressing the integrity of our relationship with God. It is the attempt to discover a manner of living that is consistent with who God created us to be. For those of same-sex orientation, being moral means rejecting sexual mores that violate their own integrity and that of others, and attempting to discover what it would mean to live by the love ethic of Jesus. 

from Homosexuality and the Bible Walter Wink