The LORD’S covenant with Abraham was sealed with the sign of circumcision.
Spiritual circumcision is of the inner person, the heart.
  Romans 2:29 “But he is a Jew who is one inwardly; and circumcision is that which is of the heart, by the Spirit, not by the letter; and his praise is not from men, but from God.”

Genesis 17:1-27
  Fact: Abram was 99 years old; God appeared to Abram promising to establish His covenant with him and his descendants.  Genesis 17:1-2

  Fact: God talked with Abram promising he would become the father of many nations.

And God changed Abram’s name to Abraham.  Genesis 17:3-5
  Fact: The LORD changed Sarai’s name to Sarah – she will be blessed and the LORD will give her a son; she will be a mother of nations and kings will come from her.  Genesis 17:15-16   

  Fact: The LORD God would make Abraham exceedingly fruitful, nations and kings would come through his descendants.  God’s covenant would extend beyond Abraham’s lifetime.  His covenant included land, all the land of Canaan, as an everlasting possession.  The LORD would be Abraham’s descendants God.  Genesis 17:6-9

  Fact: keep this covenant with the sign of circumcision between you and Me, said the LORD; Every male, eight days old will be circumcised, servants in your home or bought with money are to be circumcised. If uncircumcised, breaking the covenant.
Genesis 17:12-14  

  Fact: Abraham took all this in and laughed!  He thought in his heart, not about all these stupendous promises of God. But Abraham asked, “Will a son be born to a man 100 years old?  Will Sarah have a child at 90 years of age?” Genesis 17:17

  Fact: Abraham already had a son, Ishmael, and Abraham pleaded with God that this child would live before the LORD.  And the LORD said “no”.  Sarah will have a son, name him Isaac and the LORD promised to establish His covenant with this son and his descendants.  Genesis 17:18-19

  Fact: Abraham circumcised all the males in his camp. 
Genesis 17:24-27

  Fact: Circumcision is physical.  There is also a spiritual side to circumcision…
In the Old and New Testament, there is circumcision of the heart.  The physical side of circumcision is a picture of spiritual circumcision of the heart, circumcised by God.  

God’s Word ~ Alive!

Is your heart circumcised by God? 
Physical circumcision signifies 
a cutting away of sin in one’s life 
through faith in the Lord Jesus Christ.
Deuteronomy 30:6 “Moreover the LORD your God will circumcise your heart and the heart of your descendants, to love the LORD your God with all your heart and with all your soul, so that you may live.”