A Worshipping Community (2) (Genesis 15)

Abraham is one who has called out of his land, away from his father, and away from idolatry.  He is called to worship the one true God.  Does this mean that only those who are genetically tied to Abraham have life in Abraham?  How do we know that the blessings for Abraham are for the nations rather than one nation or nationality?

The Christmas Covenant (Genesis 15)

As protestants we champion the promise that we are justified by faith.  Justification by faith is a wonderful promise because we can be assured of enteringinto the presence of God by faith in Christ.  So, how did this blessing come to be?  Is this merely a New Testament promise?  What precedent do we see for such a promise?