Why do we experience God's great salvation?
We experience God's great salvation because of what God has done in fulfilling the covenants of Israel. Those covenant blessings overflow to us, though we have nothing to do with the covenants themselves. It is not based on our own participation in those covenants.
Les explains that all the things God did on behalf of Israel with regard to the covenants, we are now experiencing that which runs over or falls over the edges. Yes, we are experiencing the great salvation of God because of what God has done in fulfilling the covenants of Israel. But as the covenants themselves are concerned, we have nothing to do. This ties back to Genesis and the Abrahamic covenant, when God first spoke to Abram in Ur of the Chaldees and commanded him to leave his family and go to a land God would show him. By faith Abraham went, beginning God's dealing with the man from whom the nation of Israel would come. Paul writes chapters 9, 10, and 11 with special regard to Israel, and we must tie it all to the Old Testament account.