"Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all" (Romans 4:16).
Paul very skillfully explains the means by which the Gentile and Jew become justified by the faith of Abraham. In this chapter he explains, point by point, the logic that leads to the conclusion that Abraham is the spiritual father of both the Jew and Gentile, because the heirship had nothing to do with physical seed (children) or the practice of circumcision. Instead, "Abraham believed God, and it was counted unto him for righteousness" (v.3), without works (v.5), before the rite of circumcision was instituted (v.11).
Here, then, is a remarkable revelation of an inheritance pattern unknown to Mendelian genetics. Mendel, as an Austrian monk, worked out the basic principles by which natural seeds of pea plants cause inheritance of traits. The offspring of the plant crosses that he made depended upon the genetic traits inherited from the parents. But in the case discussed in our text, the offspring of God's promise to Abraham are characterized by the trait of belief, or faith. This trait leads to the forgiveness of iniquities and the covering of sins in a person's life (v.7).
What in the world is this all about? To the humanist, there is no inheritance in one's life apart from the natural transmission of genes. With the child of God, there is more. One's physical life and spiritual life can be transformed by the willing acceptance of God's promises (Genesis 15:6; 17:4). Sin in a person's life is a practice that has been permitted to emit from a person's heart (mind) (Romans 1:28; 8:7; Ephesians 4:17; Jeremiah 4:14). Acceptance of Jesus' shed blood covers our sins and makes us heirs of our "father" Abraham. KBC