wavy said:
Deuteronomy 32:21 They have moved me to jealousy with that which is not God; they have provoked me to anger with their vanities: and I will move them to jealousy with those which are not a people; I will provoke them to anger with a foolish nation.
Matthew 21:43 Therefore say I unto you, The kingdom of God shall be taken from you, and given to a nation bringing forth the fruits thereof.
Notice that it is singular, and therefore cannot be referring to the "nations" (improperly translated as "gentiles" in many places).
There were "two" nations of God's people: the house of Israel and the house of Judah (the Jews). The Jewish people are the tribe with the kings, hense Messiah, but the Israelites, namely, the tribe of Joseph had the birthright. They were to be two separate people with two different destinies until the end of time. There is a dualistic theme there--- Law and grace.
Israel, which "follows after the Law" as Paul said in Romans means the part of Israel (Judah) which follows the Law (the Jews) would become jealous over a people that are "not a people". Well, who are these? Hosea chapter one gives the answer:
Then said God, Call his name Lo-ammi: for ye are not my people, and I will not be your God. Yet the number of the children of Israel shall be as the sand of the sea, which cannot be measured nor numbered; and it shall come to pass, that in the place where it was said unto them, Ye are not my people, there it shall be said unto them, Ye are the sons of the living God.
Note here that the Israelites (not the Jews) were called "not my people"--- the greatest sense of loss of national identity ever (due to their exile) but these same people would become "sons of the living God". Now who are these? John chapter one answers that:
But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name
In other words, the nations today that are predominantly Christian are in fact physically related to the Jews and Abraham thus fulfilling the promises of "many nations". However, due to the fact that they are from the house of Israel, collectively can be referred to as a nation in regard of their origins.
Or again as Paul said:
I say then, Have they stumbled that they should fall? God forbid: but rather through their fall [ie. all Israel] salvation is come unto the Gentiles [the house of Israel, which is Gentile], for to provoke them [the house of Judah] to jealousy. The house of Israel represents God's grace part of His work and the house of Judah retains the Law part of His work.
God would not entrust the gospel to non-Israelite Gentiles or else that defeats the whole purpose of Israel altogether and cancels the whole bible story making God's word to no effect. Rather, through exile, the house of Israel became as Gentiles to that Israel could be a light unto all the Gentiles c.f. Isaiah 49:6