Paul, in his Letter to the Galatians, argues strongly that the "false brethren" were wrong in preaching the necessity of circumcision and the Mosaic Law for salvation. Their fundamental error was in thinking that the Law had redemptive power. It did not. Redemptive power lay only in the unique and all-sufficing sacrifice of Christ on the Cross. Salvation was for all, Jew and Gentile alike, based on faith in God's promises. The universality of the church was at stake here.

Today's first reading is the conclusion of Paul's argument against the false teachings. He uses the allegory of Hagar and Sarah who represent the two testaments, i.e. Hagar represents the synagogue and the slavery of the Law while Sarah the freewoman represents the Church and the freedom of the promises of God and the sacrifice of Christ on the Cross. Only adherence to Christ and not to the Mosaic Law can give salvation and righteousness. The two testaments cannot co-exist. In the Gospel Reading Jesus talks of their need for a sign. He says that His resurrection will be the only and decisive sign they will get. Just as Jonah was a warning of ruin to the Ninevites, Jesus, at His coming, will be a sign to those who have rejected Him. The warning is to repent as the Ninevites did.