If God calls His people to be like Him, to do what He is doing, and to live out His purpose so the world can see Him through us, it stands to reason that the command for circumcision in Genesis 17 reflects some sort of spiritual truth and description of God.
It’s strange and probably incorrect to say that “God is circumcised,” but there must be something about the act or the state of being circumcised (and thus the spiritual application of being “circumcised of heart”) that is tied to the identity and nature of God.