Hebrews 5:12-14 NKJV

12 For though by this time you ought to be teachers, you need someone to teach you again the first principles of the oracles of God; and you have come to need milk and not solid food. 13 For everyone who partakes only of milk is unskilled in the word of righteousness, for he is a babe. 14 But solid food belongs to those who are of full age, that is, those who by reason of use have their senses exercised to discern both good and evil.