Behind this triple division of the church [children, fathers, and young men in 1 Jn. 2] is the Old Testament sequence of offices – priest, king, and prophet. Priests are servants, who are given clear and detailed instructions for everything. They are “children,” following rules and serving. Since the church is a priesthood, John can call all his readers “children.” Kings have grown in maturity, and are called to make their own judgments about things as well as engage in battle. John’s “young men” are kings. Prophets are sages, wise men who have their senses trained to discern good and evil. They speak with authority because of that experience, and because of the Spirit in them, and so they are “fathers” to the kings and direct the priests. Every church needs each of these.
(Peter J. Leithart, The Epistles of John Through New Eyes: From Behind the Veil, pp. 77-78.)