Abraham is “the father of all who believe”. Every Christian has the privilege of calling Abraham “our father” and of inheriting the salvation promised through him. Jews have the privilege of being children of Abraham in two senses. First, all are descended from him physically. This is an involuntary circumstance marked by circumcision. No promise of eternal salvation is attached to this relationship. Second, any individual Jew may choose to “follow in the steps of the faith” of Abraham by responding to God in faith. Everything that God had given the Jew (the Law, circumcision, sacrifices, feasts and festivals) better informed their faith but none of these things removed their need to personally respond in faith. The faith that Jews and Gentiles should imitate is the faith that Abraham had before he was circumcised.
