Again, Paul made much ado about σπέρμα (sperma), which is a plural noun used in the singular. Understanding how Paul used this term and what he meant by it is essential to understanding Paul’s message to the Galatians. The law was added, “until the offspring (sperma) should come to whom the promise had been made” (v. 19). God’s promise was made to Abraham:
“And God said to Abraham, ‘As for you, you shall keep my covenant, you and your offspring after you throughout their generations. This is my covenant, which you shall keep, between me and you and your offspring after you: Every male among you shall be circumcised’” (Genesis 17:9-10).
If Isaac was not the only faithful person to follow Abraham or to issue from Abraham, then this command was not about blood lineage. To put the same idea positively, this command pertained to blood lineage only if Isaac was the only faithful person to follow Abraham. But he was not! Notice that every male in Abraham’s retinue was to be circumcised as part of this covenant. Did this mean that every circumcised male would be a faithful follower of Abraham? From what we know about Israel’s wilderness wanderings, we definitively know that every circumcised male following Abraham, his seed or progeny, was not faithful because a whole generation who followed Moses were forbidden to enter the promised land because of their faithlessness. All of this means that we must take care to read and understand God’s Word carefully. There is more to it than what first meets the eye.
At first God’s promise to Abraham appears to be to his biological children, yet God’s promise goes to only one child, Isaac, and then to Jacob, who becomes Israel. The command to circumcise all of the males in Abraham’s camp cannot be a command for blood purity because they would not have been from one biological family, as we define families today. They have been identified to be of the lineage of Shem, so the oneness suggested here must be like the oneness of the Shemites or any other people group. And biblical history is the story of significant divisions between members of the same family—Cain and Abel, Isaac and Ishmael, Jacob and Esau, etc. Over and again, the families of the Bible fight and war against one another, while Israel works to maintain familial bloodline purity. Israel argues that God’s inheritance belongs to them, to the clan of Jacob, against the sea of pagan gentiles. Yet, the Bible teaches over and over that God’s chosen people are both unwilling and unable to adhere to God’s law as provided by Moses.
Therefore, we must surmise that God did not choose them to be a model for the rest of the world to emulate, but chose them to demonstrate that, even with the help of the law provided by Moses, they would be unable to conform to God’s dictates. And yet, in spite of their foolish hardheadedness and disobedience, God would bless them. Both of these things are clearly shown in Scripture. The nation of Israel failed to manifest God’s blessings through obedience to His law, and yet the Jews as a people were blessed. They prospered in spite of their setbacks. This story is a demonstration of God’s great grace and mercy in the face of human disobedience and failure. It is a story of grace from beginning to end.
–from Galatians–Backstory / Christstory (coming in late 2015)