But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.
Ver. 5. In him verily is the love of God perfected] St John was a mere compound of sweetest love. As iron put into the fire, seemeth to be nothing but fire, so he (the beloved disciple) was turned into a lump of love. Hence he so presseth love, perfect love, to God and his people. And Jerome tells us, that living to a very great age at Ephesus, he would get up into the pulpit; and when through weakness of body he could say no more, he would say, "Little children, love one another;" Si hoc solum fiat, sufficit, If this be well done, all is done. (Jerome in cap. vi. ad Gal.)
That we are in him] In communion with him, and in conformity to him.