Expositor's Bible Commentary Commentary 1 John 4:21

"And this commandment have we from him, that he who loveth God love his brother also." — 1 John 4:21 (ASV)

The final warrant of the life of love is obedience to the teaching of Christ. He gave the command that “whoever loves God must also love his brother” (cf. Mark 12:30–31). John makes clear that obedience expresses itself in a single command. Love for God and love for neighbor are inseparable. The one is not possible apart from the other. Those who love God cannot refuse love to the image of God that meets them in their fellow believers. We are to love our neighbors in God, and God in our neighbors; this is what remaining in his love means.