Summary: Since God's love for us is profound, we are called to love each other deeply. By loving one another, God's presence is affirmed within us, perfecting His love through our actions.
Beloved, if God so loved us, we also must love one another. No one has ever seen God. Yet, if we love one another, God remains in us, and his love is brought to perfection in us.
This is how we know that we remain in him and he in us, that he has given us of his Spirit. Moreover, we have seen and testify that the Father sent his Son as savior of the world. Whoever acknowledges that Jesus is the Son of God, God remains in him and he in God. We have come to know and to believe in the love God has for us.
God is love, and whoever remains in love remains in God and God in him.