Christ's First Coming: The Seed of Isaac

Twenty-four years had passed when the Lord gave a promise to Abraham to be a great nation. Nevertheless the Lord never forgot His promise. He reiterated the same promise to Abraham with the clearer details in Gen. 17:19. He reaffirmed that the promise given to him was not only for him alone but also for the descendants of his seeds.

We need to understand that when the Lord gave the first promise to Abraham, He did not inform Abraham that the seed would come from Sarah. This is important because, during the gap of twenty-four years, somehow Sarah his wife was impatient to wait upon the Lord. As a result she asked Abraham to take Hagar her maiden in order to bear a child for Sarah. But, Gen. 17:19 gives us the clear plan of God that what Sarah did was not according to what God desired. The promised seed that would come from the line of Abraham was not through Hagar but Sarah, his legitimate wife.

The birth of Isaac was indeed the fulfilment of the promise of God to Abraham. From now onwards, the promise of God would shine brighter on Abraham because what the Lord promised would continue through the descendants of his son, Isaac. Isaac was the chosen son through whom all the nations would be blessed. Davis aptly said, “The recipient of His covenant blessings, God said unequivocally, would be a son name Isaac born to Sarah (v. 19).” The Lord did not make a new covenant with his descendants but it was a continuity of what the Lord had made with Abraham because God’s covenant was the everlasting covenant. Thus, the covenant of God with Abraham involves Isaac the son of Sarah. As Salihamer remarks, "Isaac was not to be one of the anonymous “offsprings” who was to receive the benefits of the covenant. He is here brought to the level of a participant in the original covenant: “I will establish my covenant with him as an everlasting covenant for his descendants after him” (v. 9b). Thus the identification of the covenant “offspring” of Abraham is made more specific. The descendants of Abraham who are heirs of the covenant are those through Sarah, that is, the “offspring” of Isaac."

The fact is that God said to Abraham, “I will establish my covenant with him for an everlasting covenant, and with his seed after him” (v. 19). There was no doubt that this was the anticipation of reiteration of the covenant made by God with Isaac in Gen. 26:3-5.

Thus, Gen. 17:19 was the key verse of the continuity of the covenant grace to the descendent of Abraham. This verse provides the very significant distinction to the rest of the descendants of Abraham. It is clearly stated that Isaac was the promised son to Abraham, and the covenant given by God to Abraham would continue to Isaac. In this regard, it gives the clear division that Ishmael and his descendants, and the descendants of Abraham from the sons of Keturah (25:20) will not be partakers in this covenant grace but Isaac and his descendants alone. Isaac would be the chosen line in which the Messiah would come. Henceforth the Lord would reveal it progressively through the particular tribe of Isaac’s descendants through whom the Messiah would come and be known. Luke 3:34 declares that Isaac was truly the line in which God used to fulfil His plan of salvation to save sinners from their sins.