Albert Barnes Commentary Matthew 23:15

"Woe unto you, scribes and Pharisees, hypocrites! for ye compass sea and land to make one proselyte; and when he is become so, ye make him twofold more a son of hell than yourselves." — Matthew 23:15 (ASV)

Ye compass sea and land. You take every means—spare no pains to gain proselytes.

Proselyte. One who comes over from a foreign nation, religion, or sect, to us; a convert. Among the Jews there were two kinds of proselytes:

1. Proselytes of righteousness, or those who wholly and fully embraced the Jewish religion, were baptized, circumcised, and who conformed to all the rites of the Mosaic institutions.
2. Proselytes of the gate, or those who approved of the Jewish religion, renounced the pagan superstitions, and conformed to some of the rites of the Jews, but were not circumcised or baptized.

Twofold more the child of hell. That is, twice as bad. To be a child of hell was a Hebrew phrase, signifying to be deserving of hell, to be awfully wicked.

The Jewish writers themselves say that the proselytes were "scabs of Israel," and "hindered the coming of the Messiah" by their great wickedness. The Pharisees gained them either to swell their numbers, or to make gain by extorting their money under various pretenses; and when they had accomplished that, they took no pains to instruct them, or to restrain them.

They had renounced their superstitions, which had before somewhat restrained them. The Pharisees had given them no religion in its place to restrain them, and they were consequently left to the full indulgence of their vices.