Joshua 5:2, 7 At that time the Lord said to Joshua, Make thee sharp knives, and circumcise again the children of Israel the second time….And their children, whom he raised up in their stead, them Joshua circumcised: for they were uncircumcised, because they had not circumcised them by the way.
The rite of circumcision marked Israel’s identity as God’s covenant people. It was a sign of cutting off the old life and beginning a new life with God. They belonged to God. Those Israelites that left Egypt had been circumcised, but that generation died in the wilderness. The new generation, those under 40, had not been circumcised during the wilderness wandering. Circumcision unified the people as one family belonging to the Lord. For this reason it says they were circumcised again, the second time, though for these individuals it was their first time. God sees the individual person’s need, yes, but He also sees all believers as One Body in Christ. We don’t see that, so we must believe it.
After Christ in the NT circumcision ceases and Baptism is instituted. The principal is similar: the old man, the sinful human flesh, drowns and dies daily, just as the old life is cut off; the new man, Jesus in me, arises from death to newness of life, like crossing the Jordan into the Kingdom. Circumcision is an outward sign of a new life, an inward life, eternal life. It is the circumcision of the heart