“For every one that useth milk is unskilful in the word of righteousness: for he is a babe.”
King James Version (KJV)
5:13 Every one that useth milk - That neither desires, nor can digest, anything else: otherwise strong men use milk; but not milk chiefly, and much less that only. Is unexperienced in the word of righteousness - The sublimer truths of the gospel. Such are all who desire and can digest nothing but the doctrine of justification and imputed righteousness.
Heb 5:13 For every one that useth milk . . . is a babe. Those who only understand the A B C's of Christianity are only babes in Christ, like the babes whose food is milk. [Is] unskilful in the word of righteousness. Such an one cannot handle "the word of righteousness" skillfully.