Christianity is a religion of love. But what exactly is love? First John 3:16-18 provides an answer.

This is how we know what love is: Jesus Christ laid down his life for us. And we ought to lay down our lives for our brothers. If anyone has material possessions and sees his brother in need but has no pity on him, how can the love of God be in him? Dear children, let us not love with words or tongue but with actions and in truth.

In these three verses, we see the model, definition, application, and test of true love.

The model of true love is Jesus Christ. More specifically, the model of true love is Jesus Christ crucified. “This is how we know what love is,” John writes. “Jesus Christ laid down his life for us.” In John 15:13, Jesus said, “Greater love has no one than this, that he lay down his life for his friends.” It is one thing to lay down your life for your friends, but Jesus takes things a step further. He lays down his life for his enemies. According to Romans 5:8, “God demonstrates his own love for us in this: While we were still sinners, Christ died for us.”

This model of true love leads directly to its definition. Love is self-sacrifice. Following the example of Jesus, John writes, “we ought to lay down our lives for our brothers.” Self-sacrifice, the act of laying down our lives for others, can be understood literally. Certainly Jesus understood it literally with regard to his own life. But self-sacrifice can also be understood metaphorically, as a mindset that places the interests of others before one’s own.

John shows the application of true love in terms of our use of wealth. “If anyone has material possessions and sees his brother in need but has no pity on him, how can the love of God be in him?” Charity toward the poor is not the only application of self-sacrificial love, but it is an especially clear one. Every time you give money to the homeless man on the freeway corner or write a check to your church or volunteer in the pediatric oncology wing of your local hospital, you are putting the interests of others before your own. The time, talent, and treasure you would otherwise give to yourself is being sacrificially given to others.

The test of true love is whether we are actually self-sacrificial. If we don’t show charity to the poor (and to others), John asks, “how can the love of God be in [us]?” The love of God may refer to God’s love, or it may refer to our love for God. If we fail to love the poor, then God’s love has not permeated our being, and our love for him is incomplete. Our love for others, then, demonstrates the love of God in both senses.

Having set out the model, definition, application, and test of true love, John concludes with an exhortation: “Dear children, let us not love with words or tongue but with actions and in truth.” What the world needs from Christians is not more talk about love, but simply more love.