1 John 4:16-21 (NIV)
16...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 him.
17In this way, love is made complete among us so that we will have confidence on the day of judgment, because in this world we are like him.
18There 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.
19We love because he first loved us.
20If anyone says, "I love God," yet hates his brother, he is a liar. For anyone who does not love his brother, whom he has seen, cannot love God, whom he has not seen.
21And he has given us this command: Whoever loves God must also love his brother.
To read this entire chapter of 1 John for a fuller context, click here