Even as Abraham believed God and it was counted to him for righteousness?

Notice then that the true sons of Abraham are children of faith.

And the Scripture, anticipating God's justification of the Gentiles by faith, announced the gospel to Abraham beforehand in the words, In thee shall all the Gentiles be blessed.

So then they who are children of faith are blessed with Abraham the faithful;

to the end that in Christ Jesus the blessing of Abraham might come upon the Gentiles, so that through faith we might receive the promised Spirit.

Now it was to Abraham that the promises were spoken, and to his offspring. God did not say, "offsprings" as if speaking of many, but "and to your offspring," as of one; and this is Christ.

Here is what I am saying: The Agreement originally made by God [with Abraham], with its attending promises, was not canceled when the law of Moses was given some four hundred and thirty years later.

For if the inheritance comes from law, it no longer comes from a promise; but God did give it as a free gift to Abraham by a promise.

Now the mediator or go-between [in a transaction] is not [needed] for just one party; whereas God is only one [and was the only One giving the promise to Abraham, but the Law was a contract between two, God and Israel; its validity depended on both].

And if you belong to Christ, then you are the descendants of Abraham, heirs according to the promise.

For it is written that Abraham had two sons, one by the slave woman and one by the free woman;

Now, brothers, you [Christians] are children of the promise [made to Abraham. See 3:29] just like Isaac, [Abraham's son] was.

What does the Scripture say about this matter? [It says, Gen. 21:10-12], "Get rid of the slave woman [Hagar], with her son [Ishmael]; for the son of the slave woman [Ishmael] will not inherit [what God promised to Abraham and his descendants], along with the son of the free woman [i.e., Isaac]."