In this allegory of Sarah and Hagar, it is important to notice that Paul is not dealing with the principle of evil within our hearts, but with the attempt to mingle two dispensations or methods of religious experience-the Law and the Gospel.
He says that the poor slave girl, Hagar, whom Abraham bought as a personal attendant for his wife, stands for Mount Sinai, the mountain of the Law, in the district of Arabia, from which she may have originally come. Hagar also stands for the Judaizers, whose headquarters were at Jerusalem, while their emissaries everywhere dogged the Apostle’s movements, insisting that his converts must come under the old Levitical ceremonialism. Paul says that the Galatians must choose between their slavish observance of outward ritual and a simple faith in the finished work of Jesus; and exhorts them to cast out Hagar and Ishmael, which savor of the flesh, and to give themselves to the service of the Spirit, which stands for freedom, peace, and joy in God. Let us also guard against a religious scrupulosity and subservience to the outward, and cultivate a quick sensitiveness to the Holy Spirit.