On the night of His betrayal, Jesus knew that difficult days lay ahead for His disciples. They would face many trials, and they would not have the benefit of His presence in the flesh as they had for the three years prior. Where He was going—to heaven—they could not yet come (John 13:33), and they would need to know how to live in the physical absence of their Lord. So, Jesus took the opportunity on the night of the Last Supper to give extended instruction to His disciples on what to do once He had ascended to heaven.
First, our Lord gave them the example of service to one another (vv. 14–15). In today’s passage, we read Him elaborating on this by giving them a “new commandment” to love one another (v. 34). For Jesus to call this a new commandment seems odd at first. After all, centuries earlier, the people of God had been commanded to love each other: “You shall not take vengeance or bear a grudge against the sons of your own people, but you shall love your neighbor as yourself” (Lev. 19:18). What, then, did our Savior mean when He said loving one another is a new commandment?
Dr. R.C. Sproul notes that in context, Jesus spoke these words just after Judas betrayed Him (John 13:21–30). Thus, the kind of love He enjoined upon His followers is the opposite of what Judas displayed. Jesus, Dr. Sproul writes in his commentary John, “demanded from His disciples and all who would follow Him a love that has no place for treason.” No doubt this is correct. We must also note, however, that in the same context Jesus also predicts that Peter would deny Him (John 13:36–38), which was also a betrayal of sorts. Coupled with Jesus’ elaborating that the new love commandment means loving each other as Jesus has loved us (v. 34), we see that the kind of love Jesus commands is one that endures even when someone wrongs us or even betrays us. Jesus did not stop loving Peter after his betrayal but laid down His life for Peter’s forgiveness. In like manner, though we cannot atone for sin, we are to show steadfast love to other believers.
This kind of sacrificial love that endures even when one is wronged is the mark of discipleship before the watching world (v. 35). When Christians love each other as Jesus commanded, the world will know we are His disciples. John Calvin comments, “Whoever, then, desires to be truly a disciple of Christ, and to be acknowledged by God, let him form and direct his whole life to love the brethren, and let him pursue this object with diligence.”