What does John 14:15 mean?

For such a simple statement, this verse is often exaggerated or ignored. Jesus has been reassuring the disciples as He approaches His impending death and resurrection. Part of that included encouragement—their knowledge of Him was their way to God (John 14:4–6). Those who believe in Him have the opportunity to do "greater works" than even He had done (John 14:12). The phrase immediately before this verse was a conditional promise that Jesus would do anything, provided it was asked "in [His] name." This condition prevents interpretations that make God into a robotic servant of men.

Following directly from that, Jesus connects a person's love for Him with their obedience to His teachings. There are two possible extremes to which this verse can be subjected. One is something like legalism, or works-based salvation. The other is to brush the statement aside as if a person's behavior says nothing about their eternal destiny. Both are wrong. Christ has just made it clear that He, not His followers, is the One responsible for their salvation (John 14:5–6; Titus 3:5). He has also pointed out that legitimate followers still need some level of "cleaning" from sin (John 13:10; 1 John 1:9–10).

Jesus pointedly taught that those who follow Him are obligated to show love for others (John 13:12–15, 34). That is the primary sign of faith to the outside world (John 13:35). Here, He indicates that obedience to His commands is the primary sign of our love for Him. A person cannot claim to know Christ and hate other Christians (1 John 4:20). Nor can someone claim to know Christ while disregarding His teachings (1 John 2:4).

In most earthly situations, this idea is non-controversial. True "pacifists" don't start fights. True "vegetarians" don't eat hamburgers. Incredibly, some object to the suggestion that truly born-again "Christians" don't make a habit of ignoring the teachings of Jesus. The point is not that believers are perfect—far from it (1 John 1:9–10). Nor is the lesson here that good behavior earns or keeps one's salvation (Romans 11:6). It's that a self-labelled "Christian" who lives contrary to the message of Christ is like a meat-eating warmonger who claims to be a "pacifist vegetarian."

The connection between behavior and love for Christ clearly made an impression on John, who echoes it in his letters (1 John 2:3–6; 2 John 1:6; 3 John 1:11). The guidance of the Holy Spirit is key for this obedience (John 14:16).