Next time you're near a time machine, I recommend traveling back to one of the earliest Christian churches—say, in 2nd-century Rome—and paying close attention to what you see and hear. You'll be struck, of course, by the diversity and the odd, sometimes troubling juxtapositions: Here is a community where slaves and slave owners are drinking from the same Communion cup, where the grip of Caesar's reign is loosened by a stronger cry: "Jesus is Lord." Here is a group of people who give alms to the poor, who fast and sometimes mourn for the world's pain, and sing hymns in open defiance of death, as if dying has somehow lost its terror for them. And here, perhaps most strikingly of all, is a community in which a large percentage of people are single—by choice.
The early Christians, in spite of the "family values" their differing Jewish and pagan pasts had taught them to celebrate, prized virginity. Women and men alike in the early days of the new Jesus movement gave up sex and marriage in droves. As many historians have noted, it's one of the most extraordinary things about the beginnings of Christianity. In a world where sex was as readily available as the body of the slave in your anteroom or the prostitute in the brothel down the street, a disproportionate number of Jesus-worshipers opted for celibacy. And this may be our first clue as to what a Christian "spirituality of sex" might be: Sex, for Christians, isn't necessary. It doesn't "complete" anyone. It isn't god, and it doesn't save. If the early Christians shocked Rome by their refusal to worship Caesar, they were equally shocking in their refusal to worship sex.
On closer inspection, though, the fact that the early Christians celebrated virginity wasn't just about being countercultural. They didn't want to stand out from their neighbors just for the sake of standing out. Instead, their view of their bodies and their life goals and their social structures had been upended by Jesus' resurrection. If Jesus had somehow overcome the normal course of biological reality—if his cadaver really had been transformed on Easter Sunday into a spiritual, lordly, deathless body—then everything, literally everything, was now different, the old rules about mating and marrying included. Everything the early Christians thought they knew about sex would have to be reimagined in light of the one great thing they now knew about the world: Death isn't permanent.
One of the early Christians, writing to a heretic in the 2nd century, said bluntly: "Where there is death, there is also marriage." Meanwhile, others majored on the flipside: Where there is resurrection from the dead, there can also be life without sex. If we are all headed for a life after death in which we will be crowned with joy and surrounded by a throng of fellow saints, then the expectation of finding a spouse and giving birth to a brood of offspring who will carry on your family lineage loses its urgency. Jesus' resurrection, and with it the promise of our collective resurrection, makes sexual abstinence a viable, honorable life choice. Skipping the earthly preview, believers can now jump straight to the main event of the "marriage supper of the Lamb," as the first-century prophet John called it, pinning all their hopes on the undying community to come and giving up sexual intimacy in the meantime.
Eventually, without ever losing this radical preference for celibacy, the early Christians came to realize that marriage, too, could be a way of pointing to the same resurrection hope. St. Augustine, who often (half the time unfairly, it must be said) gets a bad rap for being anti-sex, was the church father who saw clearly that finding a spouse, having sex, and starting a family could also point you toward heaven. Marriage itself, with sexual intimacy as its seal, could be a kind of parable of the way Jesus binds himself in love to the church as a whole. And when Christian married couples give themselves to one another sexually and begin to have children, they can treat those children as future citizens of the kingdom of God, baptizing them before they can even hold their eyes open, as a token of confidence that they belong, just as much as their parents do, to God's family.