Who are. — It will be seen that these words are in italics, and have to be supplied in the Greek. The Received text, which is followed in our version, also I omits a connecting particle, found in the best MSS., at the beginning of Galatians 2:16. Restoring this, a better way of taking the whole passage appears to be to supply only the word “are” in the present verse, and make the next mark a certain opposition to it: “We are (indeed) by birth Jews... but” (or, and yet), “knowing as we did that the Law cannot justify any one, we believed on Christ.” The first clause is concessive: “We grant you that we were born Jews, and not Gentiles: members of the chosen race, and not sinners.” The next clause explains why it was that, with all these privileges, the Christian, though thus born a Jew, transferred his allegiance from the Law to Christ. The reason was that the Law failed in the one great object — to justify us or obtain our acquittal in the sight of God.
By nature — i.e., by birth. The privileges of the Jew belonged to all Jews alike, simply by the more fact that they were Jews.
Sinners. — The word was almost a synonym for “heathen” in the mouth of a strict Jew. Hence there is a slight irony in its use by St. Paul. “I grant you that from our lofty position we can look down upon those poor Gentiles, sinners by virtue of mere descent.”
Of the Gentiles. — ”Of” in the sense of natural descent: “Of Gentile parentage (and therefore) sinners.”