Poets have always known that love is a fire. It burns, it melts, it consumes, it heats; it can smolder and burn low, only to burst out again with new energy. Lovers give themselves to the flames, risk and hazard all they have. “Love is a spirit all compact of fire,” Shakespeare wrote, “Not gross to sink, but light, and will aspire.” One of our own poets, Johnny Cash, agreed: “Love is a burning thing, and it makes a fiery ring.”

Theologians have known that love is fire too, so long as they paid attention to the Bible’s founding texts. Adam and Eve were created in sinless marital harmony, but since the Fall the only path back to Eden passes by the cherubim armed with flaming swords (Genesis 3:24). “Thus have I shunned the fire for fear of burning,” says Shakespeare’s aptly named Proteus.

The fiery death that threatens love does not come from external pressure so much as from lovers’ own protean fears and anxieties, from their own mercurial, disordered desires. In some marriages, perversion and infidelity dampen and quench the fire of passion, but in most it runs out in boredom, busyness, exhaustion, drudgery, familiarity, and habit, not to mention resentment and bitterness.

Behind those daily threats lurks a more fundamental danger, a more visceral fear. Octavio Paz defines eros as “a thirst for otherness.” Love is “an act of union or merging with a beloved,” and that is a terrifying prospect. As Diane Ackerman puts the question, “What if [I] get suffocated, swallowed up, dismantled?” In the sacrificial language of Solomon’s Song: What if the fire doesn’t just burn me but burns me up? What if I lose myself in the flame of desire? If love is a fire, then we have some insight into the reluctance of many to walk the path back to Eden. If the path of love runs through a circle of fire, then we are forced to ask if the reward is worth the risk, forced to ask whether we are ready to lose ourselves in loving another.

Failures in love—whether spectacular or banal—all, Ackerman notes, amount to “defenses against intimacy.” Infidelity, often a false sacrifice, is a shield against the sacrificial fire. So too is the cool indifference that characterizes many marriages.

This has been true since Eden, but the natural post-Fall instinct to recoil from intimacy is reinforced by a culture that in its most basic assumptions and habits is a massive, systematic defense against intimacy, and this is, paradoxically, most obvious in what it tells us about will and desire. The world tells me that my choices are free only if they are entirely and completely mine. If any other person influences my decision, it is no longer free, no longer valid. Other people are obstacles to my freedom, threats to my will. The flame only consumes.

As Rowan Williams has argued in his recent book Dostoevsky: Language, Faith, and Fiction, the aspiration to unqualified freedom can only kill desire. Desire is directed outward, toward another, but if union with every other, even a beloved other, ends my freedom, then desire itself enslaves.

Besides, it’s not only others who threaten my freedom. I am a threat to my own freedom. To be entirely free, my choices cannot even be constrained by my own earlier choices; my desires must remain untrammeled by earlier decisions driven by previous desires. What I said and did yesterday cannot determine what I say and do today without robbing me of my freedom.

In a world like this, there can be no narrative, no accumulation of choices, no pilgrimage, because all options must forever remain open options. No wonder marriage has become virtually impossible for many today: A lover seals his heart and arm with the name of beloved, but modern lovers reserve the right to remove the seal and choose a different beloved whenever they want another.

Dostoevsky discerned the diabolical impulse behind the nihilist claim that “all is permitted,” but he recognized also that this was only a symptom of a more fundamental diabolism: The original Satanic promise that we will be as gods, which is a promise of infinite freedom that can only end in the murder of intimacy, time, narrative, and desire.

If love is to flourish in a world organized as a defense against intimacy, a world devoted to killing love, the church must reaffirm and rearticulate its classic understanding of will and desire. It must teach lovers to give themselves to the flames, to be willing to be consumed in their union with another.

In classic Christian theology, desire and will are free when directed toward a suitable end, an end that will bring genuine happiness. I choose freely when I am pursuing a goal for my life that I should pursue. In our world, teleology is just another form of slavery, since it chains desire to a fixed end and an object outside me. As soon as I say “I choose for the sake of . . . .” I have submitted to something other than my own desires.

Our culture stokes up eros to infernal temperatures, but gives us no reason to prefer one object of desire to any other. We have no grounds for distinguishing “I want a Coke” from “I want you” from “I want to kill you.” Freedom thus paralyzes us and numbs. Our culture encourages motiveless eros, eros without object or end, which is finally indistinguishable from motiveless malignancy.

Jesus endured the cherubim’s fiery swords because he knew that on the other side was the Edenic joy of the garden and the love feast. He ascended the tree of the cross because he was confident that the sweet fruits of his bride hung ripe at the top. Burning with zeal, he threw himself onto the altar in the expectation that he would be consumed in love and joined to his bride. Jesus lost his life to gain it, and called us to follow him into the flames.

Jesus demonstrates that only desire that risks losing itself in another is strong enough to endure. Only desire that longs to be consumed in its consuming can fulfill the erotic promise articulated in the Bible—in the Song of Songs, in Ephesians, in the descent of the Bride at the end of Revelation. Only love that embraces self-immolation can bind lovers in one flesh, one spirit, one love stronger than death, one flame fiercer than Sheol.

Peter J. Leithart is pastor of Trinity Reformed Church in, Moscow, Idaho, and Senior Fellow of Theology and Literature at New St. Andrews College. His most recent book is Defending Constantine (InterVarsity Press).