So you see, the real descendants of Abraham are the men of faith.
Jesus said to him, "Salvation has come to this house today, for he too is a descendant of Abraham.
They answered, "Our father is Abraham." Jesus said to them, "If you are Abraham's children, then do what Abraham did.
and he was afterward given the mark of circumcision as the stamp of God's acknowledgment of the uprightness based on faith that was his before he was circumcised, so that he should be the forefather of all who, without being circumcised, have faith and so are credited with uprightness,
but also on ours, for it is to be credited also to us who have faith in him who raised from the dead our Lord Jesus,
nor are they all children of Abraham because they are descended from him, but he was told, "The line of Isaac will be called your descendants."
For in Christ Jesus you are all sons of God through your faith.