“These things I command you, so that you will love one another” (John 15:17, ESV).

What does it look like to carry out the kind of love Jesus describes? The Apostle Paul helps by showing what happens when we don’t live out this kind of love. In his letter to the Galatians, Paul lays out two types of sin. On the one hand he identifies gross sins, the kind we associate with outward behavior, such as sexual sins or substance abuse. But he also lays out a second type of sin—relational sin—and shows how it is just as deadly and destructive. Relational sin affects our souls to depths we never could imagine. It has an awful effect not only on our witness to the world but on the deepest parts of our being, and spreads to those around us.

Paul brings this to light in the Corinthian church by pointing out a glaring problem: the divisions among them. “I fear that perhaps when I come I may find you not as I wish, and that you may find me not as you wish—that perhaps there may be quarreling, jealousy, anger, hostility, slander, gossip, conceit, and disorder” (2 Corinthians 12:20). Note the final word in this list: disorder. This is an indication that relational sin is at work.

Each one of the things Paul lists here has to do with failing to love as Christ loved. In these terms, it’s easy to see how love can’t be just a sentimental gesture. It is a battle to be fought, and the weapons we bring are forgiveness, grace, mercy and justice.

One of the Corinthians’ conflicts involved the teaching they would accept. Some said they would follow only Peter’s direction, while others followed Paul. Paul had to tell them, “I can’t address you as mature people while you’re in this condition. It’s carnal. You’re reasoning through your flesh.”

The Greek word Paul uses for flesh indicates the skin or fatty tissue of the body. But, of course, Paul is describing the condition of their soul. He’s telling the Corinthians they’re caught up in an earthbound way of living rather than walking out the Spirit-filled life.

But as Jesus and Paul both point out, refusing to love at even the most mundane level can have huge consequences, leading to grief, alienation and regret. Strife in a relationship usually ends up affecting a larger circle of friends or family. In turn, that can extend to an entire community, as Paul showed was happening among the Corinthians. To love as Jesus loves, even in what seems like a small matter, isn’t a choice—it’s a spiritual discipline.