1 John 2:12-14 divides believers into little children, young men and fathers. William Romaine explains that Fathers are those who have gained a knowledge of Christ, which drives them with greater desire to know him more. We see this in many areas of life: a friend introduces us to some-thing, an artist, a writer, a sport, their friend. At first we may care little, but as we come to know a bit we find something to desire and so we seek to know more. Now in most things, the initial curiosity is soon exhausted. Those who become obsessed with a musical act for many years look sad to others. The object of interest simply does not warrant the attention.
It is not so with Christ “in whom are hidden all the treasures of wisdom and knowledge” (Colossians 2:3). The creature is all derivative; the original is in God. Thus, a true knowledge of God in Jesus Christ can only serve to drive a greater knowledge (which leads to the mystery of the boring preacher — it takes a special skill to make dull an exposition of God’s majesty and work).
Romaine notes that the mark of maturity is an increased desire for God:
This is the character of those believers who are stedfast in the faith, and are become fathers, able now to teach others also. They have attained to that knowledge of Christ, which is life eternal, and they are daily pressing forward. What they already know of him increases their desire to know more. And by being always conversant with him, (for without him they can do nothing) they have continual opportunities of making new discoveries. In him are laid up treasures of every thing that is great and good. His riches are unsearchable, infinite, and eternal. There is no coming to the end of them. Believers are persuaded of it, and therefore they try to dig deep into this golden mine: It is all theirs. The farther they go, the more is their faith strengthened, and the more precious Christ becomes; for they find such an excellency in the knowledge of Christ Jesus their master, that their souls hunger and thirst to know more of him. The more they attain, the more their appetite increases, and nothing can perfectly satisfy it, but the full enjoyment of Christ in glory, when they shall know, even as also they are known. Till that blessed time come, they will be growing in grace and in the knowledge of God their Savior.
This is the distinguishing mark of these fathers, they are pressing forward. They have not yet attained to the perfect knowledge of Christ, but they are going on to perfection; and they make an happy progress. God meets them in, and blesses the means, which he has appointed for their daily growth.
William Romain, Treatise Upon the Life of Faith