Romans 4:11-12 — And he received the sign of circumcision, a seal of the righteousness of the faith which he had yet being uncircumcised: that he might be the father of all them that believe, though they be not circumcised; that righteousness might be imputed unto them also:
And the father of circumcision to them who are not of the circumcision only, but who also walk in the steps of that faith of our father Abraham, which he had being yet uncircumcised.
Circumcision didn't bring righteousness, but it was a sign of righteousness imputed by faith and of Abraham's covenant with God.
Abraham had a physical relationship with Israel and a spiritual relationship with all who believe.
He was the father to those who were circumcised (Israel) and walked in faith as he did.
walk = general conduct in relation to others