Woe unto you, scribes and Pharisees, hypocrites! for you travel on sea and land to make one proselyte, and when he is made, you make him twofold more the child of hell than yourselves.
All Commentaries on Matthew 23:15 Go To Matthew 23
Hilary of Poitiers
AD 368
That they compass sea and land signifies that throughout the whole world they shall be enemies of Christ’s Gospel, and shall bring men under the yoke of the Law against the justification of faith. There were proselytes made into the Synagogue from among the Gentiles, the small number of whom is here denoted by what is said “one proselyte.” For after the preaching of Christ there was nofaith left in their doctrine, but whoever was gained to the faith of the Jews became a child of hell.
And be becomes the child of a twofold punishment, because he has not obtained remission of his Gentile sins, and because he has joined the society of those who persecuted Christ.