1 John 4:7

As the Spirit of truth is known by doctrine (thus spirits are to be tried), it is known by love likewise; and so here follows a strong fervent exhortation to holy Christian love: Beloved, let us love one another, Jo1 4:7. The apostle would unite them in his love, that he might unite them in love to each other: "Beloved, I beseech you, by the love I bear to you, that you put on unfeigned mutual love." This exhortation is pressed and urged with variety of argument: as, I. From the high and heavenly descent of love: For love is of God. He is the fountain, author, parent, and commander of love; it is the sum of his law and gospel: And every one that loveth (whose spirit is framed to judicious holy love) is born of God, Jo1 4:7. The Spirit of God is the Spirit of love. The new nature in the children of God is the offspring of his love: and the temper and complexion of it is love. The fruit of the Spirit is love, Gal 5:22. Love comes down from heaven. II. Love argues a true and just apprehension of the divine nature: He that loveth knoweth God, Jo1 4:7. He that loveth not knoweth not God, Jo1 4:8. What attribute of the divine Majesty so clearly shines in all the world as his communicative goodness, which is love.

— Matthew Henry's Concise Commentary (public domain)

Resumption of the main theme (Jo1 2:29). Love, the sum of righteousness, is the test of our being born of God. Love flows from a sense of God's love to us: compare Jo1 4:9 with Jo1 3:16, which Jo1 4:9 resumes; and Jo1 4:13 with Jo1 3:24, which similarly Jo1 4:13 resumes. At the same time, Jo1 4:7-21 is connected with the immediately preceding context, Jo1 4:2 setting forth Christ's incarnation, the great proof of God's love (Jo1 4:10). Beloved--an address appropriate to his subject, "love." love--All love is from God as its fountain: especially that embodiment of love, God manifest in the flesh. The Father also is love (Jo1 4:8). The Holy Ghost sheds love as its first fruit abroad in the heart. knoweth God--spiritually, experimentally, and habitually.

— Jamieson-Fausset-Brown Commentary (public domain)