This is my covenant, which ye shall keep, between me and you and thy seed after thee; Every man child among you shall be circumcised.
-- Gen. 17:10 (KJV)
Notice in this verse that this covenant between God and Abraham is God's covenant. We must keep His covenant because God went out of His way to make up the covenant in the first place. Since God is the One who made us, He would be able to understand which concepts man must follow in order to thrive upon this earth. Keeping His covenant is a must.
To differentiate between those who kept God's covenant from those who didn't, the physical sign of circumcision was introduced. If the Bible is false, then there would not be the scientific process called circumcision upon this planet. Those who followed God's covenant would have to be circumcised. Do the research for yourself; men that have been circumcised have less health-related problems through life than those who have not been circumcised. Notice also that only men needed to be circumcised. Hey, Africa! Stop circumcising women!
Numerical Analysis: The numerical pattern for this verse is 8,1,9,7. (8) To have a new beginning in God, know the details of His covenant. (1) To follow God, realize that keeping His covenant is mandatory. (9) To overturn evil, choose to remain in agreement with God. (7) To be complete, realize that circumcision is a sign that God's covenant with man exists.