6.  Let us see, then, how Abraham is the father of many nations Rom. iv. 17, 18..  Of Jews he is confessedly the father, through succession according to the flesh.  But if we hold to the succession according to the flesh, we shall be compelled to say that the oracle was false.  For according to the flesh he is no longer father of us all:  but the example of his faith makes us all sons of Abraham.  How? and in what manner?  With men it is incredible that one should rise from the dead; as in like manner it is incredible also that there should be offspring from aged persons as good as dead.  But when Christ is preached as having been crucified on the tree, and as having died and risen again, we believe it.  By the likeness therefore of our faith we are adopted into the sonship of Abraham.  And then, following upon our faith, we receive like him the spiritual seal, being circumcised by the Holy Spirit through Baptism, not in the foreskin of the body, but in the heart, according to Jeremiah, saying, And ye shall be circumcised unto God in the foreskin of your heart Jer. iv. 4:  Circumcise yourselves to the Lord, and take away the foreskins of your heart.  The Septuagint agrees closely with the Hebrew, but Cyril quotes freely from memory.:  and according to the Apostle, in the circumcision of Christ, having been buried with Him in baptism, and the rest Col. ii. 11, 12..