Hebrews 5:11-13 Of whom we have many things to say, and hard to be uttered, seeing you are dull of hearing. For when for the time you ought to be teachers, you have need that one teach you again which be the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat. For every one that uses milk is unskilful in the word of righteousness: for he is a babe. 

‘Of whom we have many things to say, and hard to be uttered.’ Of Christ, we have many things to say which are difficult to make clear to you, not because they are mysteries, but because you are slow to grasp the doctrines delivered to you.

‘Dull’ [Greek: nothros] dull (5:11) and slothful (6:12). It is not the truth that is so complicated; the trouble is with men who take the wrong attitude due to religious background and their traditions (Matt. 13:14-15; Acts 28:27).

‘For when for the time you ought to be teachers, you have need that one teach you again which be the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat.’ You have been professed Christians long enough to be an example through your own lives to others, but because of your laziness and dullness in grasping the truth, you must be taught a second time the first simple doctrines of Christ. You have not grown at all. You are still unweaned babes (1Cor. 3:2; 1Pet. 2:2). Milk-feeding was a metaphor used by many writers, both sacred and profane, to express the first principles of religion and science. They applied sucking to learning; infant to every beginner; and meat to those who had learned the first principles of truth. No Christian should get stuck on milk, for it is a shame that their growth is hampered and they always struggle to grow and accomplish victory in Christ and always set a bad example of what true followers of Christ must be like (1Pet. 2:21-23).

‘Unskilful’ [Greek: apeiros] inexperienced. Two characteristics of babes: Dull of hearing (5:11); and inexperienced in the Word (5:13).