Hebrews 5:12-14

For even though it is the time when you ought to be teachers, you are still lacking, so that you must be taught the things that are the basic elements of the Word of God, and so you have been made like those who are in need of milk, and not of solid food. For anyone who is still feeding on milk is still unskillful in the Word of Justice; for he is like an infant. But solid food is for those who are mature, for those who, by practice, have sharpened their mind, so as to discern good from evil.