Why Was-and is-Circumcision so Important (Genesis 17:20)

The act of circumcision became the sign of the Hebrew covenant beginning with Abraham and continuing to this day among the religious Jews. Circumcision is a removal of the foreskin on the Jewish male child, eight days after birth. From the days of the patriarchs, when a son of Abraham marries and consummates his union with his wife, the seed (sperm) in the man’s loins passes through the “mark” of the covenant; thus, the seed is marked by the covenant before it ever enters the woman. This may be why God continually uses the word seed when describing future generations of Hebrews who have not been born (see Gen. 12:7; 13:16; 17:8). God marks the seed while still in the loins of the father (note Heb. 7:9-10).

From Page 33 of the Perry Stone Hebraic Prophetic Old Testament Study Bible