Hebrews 5:9-14

9 After he had finished his work, he became the source of eternal salvation for everyone who obeys him.
10 God appointed him chief priest in the way Melchizedek was a priest.
11 We have a lot to explain about this. But since you have become too lazy to pay attention, explaining it to you is hard.
12 By now you should be teachers. Instead, you still need someone to teach you the elementary truths of God's word. You need milk, not solid food.
13 All those who live on milk lack the experience to talk about what is right. They are still babies.
14 However, solid food is for mature people, whose minds are trained by practice to know the difference between good and evil.