Thematic Bible: Who is immature

So, for my part, brothers, I could not treat you as spiritual persons; I had to treat you just as creatures of flesh and blood, as babies in Christian living. I fed you with milk, not solid food, for you were not ready for it. Why, you are not ready for it now, for you are still worldly. For when there are still jealousy and quarrels among you, are you not worldly and living on a merely human level?

I have much to say to you about this, but it is difficult to make it clear to you, because you have become so slow of apprehension. For although from the length of your Christian experience you ought to be teaching others, you actually need someone to teach you over again the very elements of Christian truth, and you have come to need milk instead of solid food. For anyone who is limited to milk is unacquainted with Christian teaching, for he is only an infant.