John 8:37-39

John 8:37-39. I know that ye are Abraham’s seed; but ye seek to kill me, because my word hath no place in you. I speak that which I have seen with my Father: and ye do that which ye have seen with your father. They answered and said unto him, Abraham is our father. Jesus saith unto them, If ye were Abraham’s children, ye would do the works of Abraham.

The real descendants of "the father of the faithful" are themselves faithful; that is, believers. The father of believers has believers for his children: "If ye were Abraham’s children, ye would do the works of Abraham." Our Lord had admitted that these Jews were Abraham’s seed according to the flesh; but he proved that they were not Abraham’s seed in the high and spiritual sense, since they were not like him whom they claimed for a father.