The Epistles of John, assigned to the writer of the Fourth Gospel and the Revelation, testify that God is love and that love is the test of religion. Second John is written to “the elect lady and her children,” probably a church; Third John is addressed to “the beloved Gaius.”

1 John 4

4:20 If a man say, I love God, and hateth his brother, he is a liar: for he that loveth not his brother whom he hath seen, how can he love God whom he hath not seen?