Hebrews 5:12-14 (New International Version)

¹²In fact, though by this time you ought to be teachers, you need someone to teach you the elementary truths of God's word all over again. You need milk, not solid food! ¹³Anyone who lives on milk, being still an infant, is not acquainted with the teaching about righteousness. ¹⁴But solid food is for the mature, who by constant use have trained themselves to distinguish good from evil.