Verse 29 says, “But as then he that was born according to flesh persecuted him that was born according to Spirit, so also it is now.” The two kinds of children brought forth by the two covenants are different in their natures. Those brought forth by the covenant of law are born according to flesh; those brought forth by the covenant of promise are born according to Spirit. The children born according to flesh have no right to participate in God’s promised blessing, but the children born according to the Spirit have the full right. The Judaizers were the former kind of children; the believers in Christ are the latter. The children of promise (v. 28) are born according to Spirit, God’s Spirit of life, who is the very blessing of God’s promise to Abraham (3:14).
Paul says that the one born according to flesh persecuted the one born according to the Spirit. This indicates that Ishmael persecuted Isaac (Gen. 21:9). Furthermore, the Judaizers, the descendants of Abraham according to flesh, also persecuted the believers, the descendants of Abraham according to the Spirit, as Ishmael did Isaac. The same is true today. Today’s Ishmaels, those according to flesh, are persecuting the real Isaacs, the children according to the Spirit.
In verses 30 and 31 Paul concludes, “But what does the Scripture say? Cast out the maidservant and her son; for the son of the maidservant shall by no means inherit with the son of the free woman. Wherefore, brothers, we are not children of a maidservant, but of the free woman.” The Judaizers under the slavery of law are the sons of the maidservant, who shall by no means inherit God’s promised blessing—the all-inclusive Spirit. The believers of the New Testament under the freedom of grace are the sons of the free woman, who shall inherit the promised blessing of the Spirit. We, the believers in Christ, are not children of law under its slavery, but children of grace under its freedom to enjoy the all-inclusive Spirit with all the riches of Christ. It is important to remember that the free woman represents grace and the promise, whereas the maidservant, Hagar, represents the law and also the efforts of the flesh. Thus, the law brought forth children according to the flesh, but the promise and grace brought forth children according to the Spirit.
The conclusion of chapter four is very similar to that of chapter three. Paul ends chapter three by saying that we “are Abraham’s seed, heirs according to promise.” Then he closes chapter four with these words: “Wherefore, brothers, we are not children of a maidservant, but of the free woman.” At the end of chapter three, we see that we are sons of Abraham, but at the end of chapter four, that we are children of the free woman, those who inherit the promise. Actually, these two chapters speak of the same thing viewed from different angles.
As we consider the matter of two covenants and two kinds of children, we need to be impressed with God’s promise, grace, Christ, the Spirit, and the children according to Spirit. In contrast to these, we have the law, flesh, slavery, and the children according to the flesh. The children according to the flesh are those held in slavery. In this message I am burdened that we all be impressed with the five positive matters of promise, grace, Christ, the Spirit, and the children according to the Spirit.
The promise given to Abraham was the unveiling of God’s desire. When God made the promise to Abraham, He opened His heart and unveiled the desire of His heart. Although man had fallen and was under the curse, God’s desire was to bless all nations. His desire was to give Himself as a blessing to the nations. God had told Abraham that in Him all nations would be blessed (Gen. 12:3). This promise was given over against a certain background. At the time the promise was given, all the nations were under the curse. No doubt, Abraham realized this. Then, suddenly, the God of glory appeared to him and promised that in him all the nations would be blessed. What a tremendous word this was! When the God of glory appeared to Abraham in Ur of the Chaldees, Abraham was attracted. He was charmed. Because he was attracted by God, Abraham could follow Him out of Chaldea. Then, when Abraham was sojourning in the land of Canaan, God promised to give the land to Abraham’s seed. Therefore, with God’s promise to Abraham there are two main aspects: the aspect of the nations being blessed and the aspect of the good land. On the one hand, the nations would be blessed through Christ’s redemption. On the other hand, Christ, typified by the good land, is the embodiment of the Triune God as the all-inclusive life-giving Spirit as our enjoyment and bountiful supply. God’s promise to Abraham with these two aspects was the unveiling of the desire of God’s heart.
God’s promise to Abraham involves much more than justification by faith. Yes, we are told that Abraham believed God and that it was reckoned to him as righteousness (3:6). However, we need to see that God’s dealing with Abraham involved much more. The gospel preached to Abraham was actually the unveiling of God’s heart.