Galatians 5:3

Verse 3. For I testify again. Probably he had stated this when he had preached the gospel to them at first, and he now solemnly bears witness to the same thing again. Bloomfield, however, supposes that the word again here palin means, on the other hand; or furthermore; or, as we would say, "and again." That he is a debtor to do the whole law. He binds himself to obey all the law of Moses. Circumcision was the distinguishing badge of the Jews, as baptism is of Christians. A man, therefore, who became circumcised, became a professor of the Jewish religion, and bound himself to obey all its peculiar laws.