Romans 11:17

But if some of the branches were broken off, and thou, being. wild olive, wast grafted in among them, and didst become partaker with them of the root of the fatness of the olive tree; "some of the branches were broken off" -i.e. Jews that rejected the gospel (Romans 11:20). These were the 'sons of the Kingdom' who Jesus said would be 'cast out' (Matthew 8:11).

"thou, being. wild olive, wast grafted in among them" -i.e. Gentiles that had come to Christ. (Ephesians 2:11)

"didst become partaker with them..of the fatness of the olive tree" -'became partaker with them of the rich root' (NASV). The root is the source of the fatness. Believing Gentiles had become partakers of all the Messianic promises, and the 'seed' promise to Abraham. (Galatians 3:28; Romans 15:27) What was promised to Abraham, Isaac and Jacob, the believing Gentile now receives!

"Partaker" -'came to share with them' (TCNT). 'Them' in these verses apparently are believing Jews.

Point to Note:

This section of Scripture really throws. monkey wrench into Premillennialism. For if the 'land promise' to Abraham and his descendants was never fulfilled, then such land isn't promised to unbelieving Jews (for God broke them off, they don't partake in the rich root anymore!), but rather to believing Jews and Gentiles, i.e. the Church! How can God deny believing Gentiles land also, when they have become grafted in and an actual partaker with believing Jews of the promises of God???? Of course God did fulfill his promise of land to the nation of Israel. But the above just shows how contrary to Scripture Premillennialism is.