Albert Barnes Commentary Hebrews 5:13

"For every one that partaketh of milk is without experience of the word of righteousness; for he is a babe." — Hebrews 5:13 (ASV)

For every one that useth milk. This refers to the food of children. The apostle here has in mind those Christians who resemble children in this respect: they are not capable of receiving the stronger food suitable for those of mature age.

Is unskilful. This means inexperienced; one who lacks skill to perform anything. The word is properly applied to someone who lacks experience or skill, or who is ignorant. Here it does not mean that they were not true Christians, but that they did not have the experience or skill necessary to enable them to understand the higher mysteries of the Christian religion.

In the word of righteousness. This refers to the doctrine concerning the way in which people become righteous, or the way of salvation by the Redeemer. (See Barnes on Romans 1:17).

For he is a babe. That is, in religious matters. He understands the great system only as a child might. It is common to speak of "babes in knowledge" as denoting a state of ignorance.