Israel, the Israel "of Israel", the Gentile, and the Church
I wanted to visually show how I see this verse, Romans 9:6, and how it looks in relation to the present program and purposes of God... whereby He is revealing His righteousness through faith in Jesus Christ, to all and on all who believe. (Romans 3) He is creating in Himself one new man from the two... that He might reconcile them both to God in one body... (Eph. 2) This is the Church.
There is no millenium in this picture. Notice that the defining characteritic of the church is the blue hat. It doesn't matter what nation you come from. You must be born again by grace through faith and you need the blue hat. Note that there are no yellows in the church. You must have faith - being from the nation Israel alone will get you nowhere in Christ's church.
The church is not Israel and it is not the Israel "of Israel" because there are gentiles in the church. The Israel "of Israel" is part of the church in this present time, but it is not the whole church.