Hebrews 5:11-14 (WEB) About him we have many words to say, and hard to interpret, seeing you have become dull of hearing. 12 For although by this time you should be teachers, you again need to have someone teach you the rudiments of the first principles of the revelations of God. You have come to need milk, and not solid food. 13 For everyone who lives on milk is not experienced in the word of righteousness, for he is a baby. 14 But solid food is for those who are full grown, who by reason of use have their senses exercised to discern good and evil.
V11 “About him we have many words to say, and hard to interpret, seeing you have become dull of hearing.” Him is Melchizedek. Some believe that Melchizedek was Shem, the son of Noah, or was a Christophany of Jesus Christ. Melchizedek was a king and priest of the one God that Abraham also worshipped. Salem is usually identified as Jerusalem. Many words to say refers to his life is very interesting though obscure. The words themselves are hard to interpret. The idea here it is difficulty to clearly explain Melchizedek. The idea is “About him we have many words to say, and difficult to explain, because you have become dull of hearing.”
The difficulties are due to the hearers and readers of this letter becoming “dull of hearing.” They hear what is taught but don’t want to understand, are not paying attention or do not plan on applying it to their lives. There is the idea of willful ignorance and indifference. The Greek word for “dull” is (G3576) νωθρός nōthrós, which means slow, sluggish, slothful. (Theological Dictionary of the New Testament (Abridged – Little Kittel)) “The word nōthrós, meaning ‘sluggish,’ ‘obtuse,’ occurs in the NT only in Hebrews. In 5:11 the author cannot deal with profounder themes because his readers are slow to hear and receive. This is because they lack the vitality of assured and persevering faith (6:12). Those who are exhausted in both breathing in (hearing) and breathing out (confident believing) are nōthroí. [H. PREISKER, IV, 1126]” Compare John 8:43 and Matthew 13:15.
V12 “For although by this time you should be teachers, you again need to have someone teach you the rudiments of the first principles of the revelations of God. You have come to need milk, and not solid food.” The dullness reveals itself through their not being teachers. Though they have learned, they either forgot or haven’t maintained knowledge. Because of their dullness, they nearly have to start at the beginning. The Hebrews writer shames them for their lack of faithfulness and increase in spiritual knowledge.
V13 “or everyone who lives on milk is not experienced in the word of righteousness, for he is a baby.” All Christians need to start with the basics of doctrine and Bible knowledge. It is Christianity 101. After this is taught, then we must learn more. Bible study must be the priority. By Bible study I mean without the commentaries until after determining what the passage means. A good reference Bible as Thompson Chain or a good translation with a topical bible such as Manser’s “Dictionary of Biblical Themes.” We first learn the Gospel of which the basics can be learned in a few minutes. Then an introduction to the Bible including first of all Bible Interpretation such as Dr. David L. Cooper (Biblical Research Society) or Dr. Cooper Abrams III (Bible Truth Org). From there we learn more of Scriptures and further teaching in what we believe (doctrine), the Christian way of life, the Christian worldview, and Christian rules (Law of Christ–Galatians 6:2). Most of which can be understood from the Bible. The Word of Righteousness is the Bible where we learn what righteousness is and how to live it. A start for beginning Christians’ Beliefs is Blue Letter Bible, especially on “study” tab. Step Bible is also a good online study Bible.
V14 “But solid food is for those who are full grown, who by reason of use have their senses exercised to discern good and evil.” Those who know the basics can move on to deeper studies. An example would be Dr. Arnold Fruchtenbaum at Ariel Ministries under the “store” tab. His commentaries are excellent. Also, the Holman Commentary Set for the whole Bible is good.