1 John 3:10

3:10 By this the children of God and the children of the devil are revealed: Everyone who does not practice righteousness – the one who does not love his fellow Christian – is not of God.

1 John 4:9

4:9 By this the love of God is revealed in us: that God has sent his one and only Son into the world so that we may live through him.

1 John 4:20

4:20 If anyone says “I love God” and yet hates his fellow Christian, he is a liar, because the one who does not love his fellow Christian whom he has seen cannot love God whom he has not seen.