Q. What is the Abrahamic covenant mentioned in Genesis 17:7, 17:13 and 17:19? What aspect of the Abrahamic covenant is everlasting? Why don’t Christians practice circumcision if the Abrahamic covenant is everlasting?
Here’s what I say about that passage in my study guide to Genesis. I believe these observations address your concerns. Basically, God is not making a new covenant with Abraham here. Rather, God is ratifying the covenant that he made with him earlier. (You can read or download the whole study guide for free at this link.)
God speaks to Abram to renew and extend his covenant with him. God introduces himself by a new name, El Shaddai (“God Almighty”). This name expresses his strength and power to fulfill his promises.
God also gives Abram and Sarai new names. Abram means “exalted father.” God changes this to Abraham, “father of a multitude,” to express his purpose to make Abraham “very fruitful,” the “father of many nations.” And God changes the name Sarai to Sarah, a more recognizable form of the word meaning “princess,” since “kings of peoples will come from her.” Through these new names, God expresses and guarantees the purposes that he will fulfill in their lives. The names are, in effect, miniature covenant vows.
In addition to guaranteeing his covenant with new names, God also guarantees it with a sign, just as he gave the sign of the rainbow for his covenant with Noah. God uses the sign of circumcision to guarantee his covenant with Abraham, to symbolize how this covenant will not be just with Abraham, but also with his son and with all of their descendants, perpetually. [That is what “everlasting” means here.] The sign would be replicated in the bodies of all future generations: “My covenant in your flesh is to be an everlasting covenant.”
Descendants of Abraham who practiced circumcision were showing that they belonged to the community that was created by God’s covenant with their ancestor. But a new kind of community has now been created by God’s covenant with Jesus. It has a new sign of its own. Baptism is the sign of belonging to the community of Jesus’ followers.
Baptism symbolizes God’s covenant obligations to us by illustrating his promise to raise us from the dead, both physically (when we die) and spiritually (as we experience new life in Christ). Baptism symbolizes our covenant obligations to God by illustrating the way followers of Jesus are supposed to die to sin and rise to a new life of faith and obedience.