By this we know that we love the children of God: when we love God and keep His commandments.
Believers know they love God's children when they love God and keep His commandments.
This verse shows that love for fellow believers is inseparable from devotion to God.
1Everyone who believes that Jesus is the Christ has been born of God, and everyone who loves the Father also loves those born of Him. 2By this we know that we love the children of God: when we love God and keep His commandments. 3For this is the love of God, that we keep His commandments. And His commandments are not burdensome, 4because everyone born of God overcomes the world. And this is the victory that has overcome the world: our faith. 5Who then overcomes the world? Only he who believes that Jesus is the Son of God. 6This is the One who came by water and blood, Jesus Christ — not by water alone, but by water and blood. And it is the Spirit who testifies to this, because the Spirit is the truth. 7For there are three that testify: 8the Spirit, the water, and the blood — and these three are in agreement.