Adam Clarke's Commentary on the Bible

Verse 1 (James 3:1)

Be not many masters - Do not affect the teacher's office, for many wish to be teachers who have more need to learn. There were many teachers or rabbins among the Jews, each affecting to have The truth, and to draw disciples after him. We find a caution against such persons, and of the same nature with that of St. James, in Pirkey Aboth, c. i. 10: Love labor, and hate the rabbin's office.

This caution is still necessary; there are multitudes, whom God has never called, and never can call, because he has never qualified them for the work, who earnestly wish to get into the priest's office. And of this kind, in opposition to St. James, we have many masters - persons who undertake to show us the way of salvation, who know nothing of that ways and are unsaved themselves. These are found among all descriptions of Christians, and have been the means of bringing the ministerial office into contempt. Their case is awful; they shall receive greater condemnation than common sinners; they have not only sinned in thrusting themselves into that office to which God has never called them, but through their insufficiency the flocks over whom they have assumed the mastery perish for lack of knowledge, and their blood will God require at the watchman's hand. A man may have this mastery according to the law of the land, and yet not have it according to the Gospel; another may affect to have it according to the Gospel, because he dissents from the religion of the state, and not have it according to Christ. Blockheads are common, and knaves and hypocrites may be found everywhere.

- Adam Clarke's Commentary on the Bible