Rom.4:12- And Abraham is also the spiritual father of those who have been circumcised, but only if they have the same kind of faith Abraham had before he was circumcised.
Circumstances and situations change, people in the world don’t. One of the issues Paul faced throughout his ministry was people believing that circumcision was necessary for salvation. Circumcision was the mark of Jewishness and in Paul’s world was the evidence of being right with God. One of the first things to happen to a non Jew who was converting to Judaism was circumcision. As the church began to grow significantly in the gentile world in those days this belief was creating a firestorm. To the Jew, circumcision proved you were approved by God. Thousands of gentiles who were saved in Paul’s ministry had not followed suit, they believed they were saved by grace through faith and circumcision was not even a consideration for them.
In today’s world we deal with similar issues with water baptism. Many churches believe and teach that Christians baptize their children as infants guaranteeing their Christian faith. Others think baptism is the magic formula, you know “once you are wet you are set”. Water baptism is something that happens after conversion. Actually Abraham’s testimony was just like that. Abraham believed God and it was counted as righteousness to him several years before he was circumcised. So circumcision was given as a sign of Abraham’s faith, he was circumcised after he believed in the Lord. Here is how Martin Luther describes this passage.
“These words tell us that Abraham was justified before he was circumcised. Afterwards he received circumcision as a seal (of his justification). All this God did in order that we may know that throughout the world all those who followed Abraham’s faith shall be his children. In this way (by faith) also the Jews will become his children, namely, if besides the circumcision of the flesh, they receive also the circumcision of the heart. According to the flesh they already are his children, but they must become also his spiritual children, in order that they may be Abraham’s children not only according to the flesh, but also according to the spirit.”
Abraham was praying for a family, he got way more than he bargained for. He was promised that all the nations of the earth would be his heirs. He had no way of understanding the ramifications of that promise. He became the biological father of the nation of Israel. He also became the father of this new spiritual race of humans who came to the Lord by grace through faith. Through the gospel all the nations and ethnic groups of the world are becoming sons and daughters of Abraham through faith in Christ Jesus.