"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." Christ also says: "Moses, therefore, gave unto you circumcision; (not because it is of Moses, but of the fathers.)" Abraham was not a Jew when God covenanted with him, any more than you, madam, were Mrs.Ford, when, at the age of sixteen, as you have told me, you entered into covenant with God.

That covenant had chief respect to your immortal soul, and yet it reached in its influences to all the conditions of that soul while here in the flesh.
So God covenanted with Abraham as a believer, not as a mere national ancestor; yet temporal and spiritual blessings came in rich measures upon his immediate descendants.

But we read, "So then as many as be of faith are blessed with faithful," that is, believing, "Abraham." "And if ye be Christ's, then are ye Abraham's seed, and heirs according to the promise." Can anything be plainer than this?
_Mrs.Ford._ My father was a minister, you know, sir, and he used to preach a great deal on this subject.
_Pastor._ Let us hear your understanding of these passages, Mrs.Ford.
"I am afraid," said she, "I cannot tell you just what he used to say.
But my idea of it is this: Though Abraham was the founder of the Hebrew people, he was no more a Jew than a Gentile in his covenant with God, for it was as believer the great believer, that God made a covenant with him.

So that he was not circumcised as a Jew, but, as the Bible says, to have a seal of the righteousness which he had by faith.

God made a covenant with him as a believer, to be his God and the God of his children, as the children of a believer, not a Jew; so that all believers are blessed with believing Abraham, by having the same covenant extended to them.