Don't these things happen among you just as they happened with Abraham? He believed God, and that act of belief was turned into a life that was right with God.
Is it not obvious to you that persons who put their trust in Christ (not persons who put their trust in the law!) are like Abraham: children of faith?
It was all laid out beforehand in Scripture that God would set things right with non-Jews by faith. Scripture anticipated this in the promise to Abraham: "All nations will be blessed in you."
So those now who live by faith are blessed along with Abraham, who lived by faith - this is no new doctrine!