Both Sarah and Rebekah came from the idolatrous land of Chaldea (Gen. 11:31; 24:4) to the place of God’s promise. One became the mother-in-law and symbolizes the new covenant of grace; the other became the daughter-in-law and symbolizes the church of the New Testament.
Sarah, Abraham’s wife, and Hagar, Abraham’s concubine, symbolize two covenants (Gal. 4:24). Hagar symbolizes the old covenant of law, and Sarah, the new covenant of grace. That is, Sarah symbolizes grace, which originally was to be given to man by God (Rom. 5:15); Hagar symbolizes the law, which was added later (Rom. 5:20). Those who desire to keep the law by themselves are brought under slavery by the law (Gal. 4:24b; 5:3). Those who inherit grace by faith (Gal. 4:23b, 30b) are made sons of freedom by grace. The old covenant, symbolized by Hagar, is from Mount Sinai, which belongs to the law and brings forth children unto slavery. The new covenant, symbolized by Sarah, is from the Jerusalem above, which is free and belongs to grace, and which brings forth children of God that they might be His heirs. She is the mother of the New Testament believers. We are not children of the maidservant, Hagar, who symbolizes the old covenant, and we are not under the slavery of law. Rather, we are children of the free woman, Sarah, who symbolizes the new covenant, and we enjoy all the riches of Christ in grace.
Sarah symbolizes the new covenant of grace; that is, she symbolizes the heavenly Jerusalem, the Jerusalem above, as the mother of the believers (Gal. 4:26). Thus, this woman Sarah, as the wife, symbolizes the new covenant and grace, the content of the new covenant; she also symbolizes the Jerusalem above, and our mother. The wife, like the New Jerusalem, which is the wife of the Lamb (Rev. 21:2, 9), is the heavenly Jerusalem (Heb. 12:22). This heavenly Jerusalem, the Jerusalem above, is our mother, the grace through which we were born. This grace is the content of the new covenant (just as the law is the content of the old covenant—John 1:17). And this new covenant is the woman. Therefore, these six items—the woman, the wife, the new covenant, the grace of the new covenant, the Jerusalem above, and our mother—are all matters of the spiritual life that pertain to the union of the Triune God with man to produce the believers for the constituting of the church.
Sarah is a positive, spiritual model in the matter of submitting to her husband. When Abraham went down to Egypt because of the famine, he said to Sarah, his wife, “Behold now, I know that thou art a fair woman to look upon: therefore it shall come to pass, when the Egyptians shall see thee, that they shall say, This is his wife: and they will kill me, but they will save thee alive. Say, I pray thee, thou art my sister: that it may be well with me for thy sake; and my soul shall live because of thee” (Gen. 12:11-13). A weak Abraham lied by telling the truth (Gen. 20:11-13), sacrificing his wife in order to save his own life. And yet Sarah accepted his idea, completely obeying and submitting herself to her husband. Later, Abraham repeated his old failure of sacrificing his wife in order to save himself. Sarah again obeyed and submitted herself to him and did not complain at all (Gen. 20:1-2).
Sarah obeyed and submitted herself to her husband with a meek and quiet spirit (1 Pet. 3:4). She not only obeyed Abraham but also submitted herself to him, even calling him “my lord” (Gen. 18:12). Thus she became a positive, spiritual model. Therefore, the holy women who hope in God and who submit themselves to their husbands are her daughters (1 Pet. 3:5-6).