But whoso keepeth his word — His commandments. Verily in him the love of God — Reconciled to us through Christ. Is perfected — Is perfectly known. Hereby — By our keeping his word. We know that we are in him — So is the tree known by its fruits. To "know him," to be "in him," to "abide in him," are nearly synonymous terms; only with a gradation, — knowledge, communion, constancy.
Related Commentaries of 1 John 2:5
1 John 2:5
5 But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.