This is how we know what love is: Jesus Christ laid down his life for us. And we ought to lay down our lives for our brothers and sisters.
Whoever claims to love God yet hates a brother or sister is a liar. For whoever does not love their brother and sister, whom they have seen, cannot love God, whom they have not seen.
And so we know and rely on the love God has for us. God is love. Whoever lives in love lives in God, and God in them. This is how love is made complete among us so that we will have confidence on the day of judgment: In this world we are like Jesus. There is no fear in love. But perfect love drives out fear, because fear has to do with punishment. The one who fears is not made perfect in love.