are the children of Abraham. And the scripture, foreseeing that God would
justify the Gentiles through faith, preached before the gospel unto Abraham,
saying, In you shall all nations be blessed. So then they who are of faith are
blessed with faithful Abraham.
The actual references for this "sermon preached by Scripture" are Genesis 18:18, Genesis 22:18, Genesis 26:4. No, the Gospel is no "new thing," but was ordained from the foundation of the worlds. This has great impact on the validity of Scriptures, and ties in both with the statement of Jesus that he came to fulfill Scripture Matthew 5:17 and with the endorsement of the Old Testament by Paul in 2 Timothy 3:16.
Today, we have three of the worlds religions that came from Abraham's children; Judaism, Islam, and Christianity. These religions cover 55% of the world's population.