Hebrews 5:11-14

¹¹ “Concerning him we have much to say, and it is difficult to explain, since you have become poor listeners. ¹² For though by this time you ought to be teachers, you have need again for someone to teach you the elementary principles of the actual words of God, and you have come to need milk and not solid food. ¹³ For everyone who partakes only of milk is unacquainted with the word of righteousness, for he is an infant. ¹⁴ But solid food is for the mature, who because of practice have their senses trained to distinguish between good and evil.”

The author of Hebrews is chastising his readers for their lack of maturity in the Gospel. They ought to have understood the Gospel enough by this point to teach it clearly to others. However, many of these people were stuck on milk. They were barely grasping the Gospel if at all. They ought to have graduated to the word of righteousness, the reality of their righteousness in Christ and yet many did not understand their identity. The mature, however, have their senses trained to distinguish between law and Gospel, as well as good sound doctrine versus false teaching.