John moves from right belief about Jesus (4:1-6) to right conduct toward one another (4:7-21). For the third time he commands us to love one another (cf., 2:7-11; 3:11-18). The word "love" occurs twenty-seven times in this passage. In between admonishments to love one another, John illustrates God’s love for us and encourages us that mature love brings a lasting hope in God’s promise of eternal life.

Love One Another (vv. 7-8)
Since our nature derives from our Parent, John takes it for granted that we will be like our Father.

Throughout John’s writings, he makes simple statements that describe God’s nature: God is "truthful" (3:33); God is "spirit" (Jn. 4:24); God is "light," (1 Jn. 1:5); "faithful and just" (1 Jn. 1:9); "greater than our hearts" (1 Jn. 3:20); "God is love" (4:8; 4:16). In essence, God is a non-material, personal, loving being who is morally perfect, honest, and fair in all his judgments as he pardons for the sake of establishing and maintaining a relationship with us. These features ring true, to some extent, for members of God’s family.

To Consider: The excellencies of God’s love are beyond imagination! God’s love is unconditional (Deut. 7:6-8; Jn. 15:12; 2 Tim. 1:9), unmerited (Hos. 14:4; Rom. 5:6, 8), incomprehensible (Ps. 108:4; Eph. 3:19); everlasting (Ex. 15:13; Ps. 119:76; 136; Is. 54:10; Jer. 31:3; Lam. 3:32), tender and gentle (Ps. 86:5; Is. 49:15; Hos. 11:1, 3-4; Zeph. 3:17), our highest goal in life (Ps. 63:3; Pr. 19:22).

God's Love For Us (vv. 9-16)
Since God is "love," then what is love? When defining love, John thinks in terms of initiative and sacrifice. When defining love, John thinks in terms of Jesus.

Yet, John did not tell us to love God in return. Instead, he insists that we love one another. Love desires to give, not get. Love sacrifices all, not some.

Love is God's motivation behind the self-disclosure of God in Jesus (Jn. 3:16). In expressing God’s salvific love, Jesus’ humility in death, as well as his life, was involved. Authentic, biblical love for one another demands no less of a sacrifice.

In John’s community, some were concerned only about a vertical relationship with God, at the expense of nurturing horizontal relationships with God’s family. Consequently, they were hateful and indifferent toward others. The goal of love, however, is practical. Love’s intended result is always realized ("that we might live through him"). So too, when we express God’s love for others, the effects must be obvious (3:17).

God’s love is proactive, not reactive. Human love for God and others is the result of a direct encounter with the reality of God’s salvific love (also, v. 19). All other forms of human love only hint at this reality. When believers love one another with the same love God had for us at the cross, the peak of perfect love has been reached.

Although God cannot be seen (also, Jn. 1:18), he can be perceived in the genuine expressions of love among his people.

If the source of love is God, then the inspiration to love is his Spirit. How it is that "we live in him, and he in us" is by the Holy Spirit whom God has given us. By the very presence of God’s Spirit in our lives, we can have assurance of a relationship with God.

The Spirit’s presence, faithful witness to Jesus, and loving others are all evidences of being in God’s family (3:23-24).

To Consider: For John, it is impossible to divorce the doctrinal test from the social test. To believe the right things about Jesus’ identity is to be transformed by God’s love, since Jesus is the full expression of the love of God.

Confidence in God's Love (vv. 17-18)
God’s "complete" love is better translated "mature" love. In 2:5 mature love is realized by an obedient lifestyle. Here, mature love (4:12, 17) is demonstrated by love for others.

The result of walking in obedience and loving others is confidence on the day of judgment. Our future confidence is tied to our present reality of loving others and obedient living. For the Apostle John, boldness in the face of God’s judgment is grounded in obedience and love.

Being "in this world" is no hindrance to our walk, because we are like Jesus whose life was the perfect expression of love and obedience. Being in the world is where victory is realized (cf., 2:13-17; 5:4-5, 19).

All fear is banished when the believer’s life reflects the mature, sacrificial love God has shown in the life of Jesus. Moreover, our love for God provides courage before him, since it’s impossible to love and fear him at the same time.

Love One Another (vv. 19-21)
The ultimate ground or basis for our assurance is not found in our love for others, but in God’s love for us. Mature human love is always a response to divine love. Verse 19 not only states implicitly that we can love because God loved us, but also that we must love because God has so loved us.

Yet, some in John’s community claimed to love God while hating others. John says it’s impossible to experience God’s love and not express it. The requirements of love are never complete by loving God without also loving those born of God.

For John, to withhold love for others indicates that love for God is impossible (cf., 3:17). John demonstrates his basis for authority by reaffirming the love command that Jesus gave (cf., Mt. 12:28-34; Jn.15:12, 17; 13:34-35).

Summary
If we love God, we will obey him and, to obey God is to love others. In loving others as Christ loved us, we gain confidence that we belong to God’s family. Therefore, love is a compelling means of increasing assurance of salvation.

 1 John 5:1-5