ISB ~ Romans 4 v11

father of all who believe:The fatherhood of Abraham is defined by imitation rather than generation. To be a part of his family is to share his faith, not necessarily his physical lineage (4:12, 16).

without being circumcised:Given Paul’s comments about true circumcision in 2:25-29, he is saying that Abraham is the father of true Jews, not all Jews. Jesus makes a similar point in Jn 8:39.