Hebrews 5:11-14 - Advanced Teaching Hindered By Immaturity

¹¹ I have much to say to you about Him, but it is difficult to make it clear to you, since you have become so dull in your spiritual senses. ¹² For although you ought to be teachers of others because you have been Christians so long, you actually need someone to teach you over and over again the very elements of the truths that God has given us, and you have gotten into such a state that you are in constant need of milk instead of solid food. ¹³ For everyone who uses milk alone is inexperienced in the message of right-doing; he is only an infant. ¹⁴ But solid food belongs to full-grown men who on account of constant use have their faculties trained to distinguish good and evil.