Jack I think most Christians in the modern day have accepted that Christians are the new testament Israel. When Paul was brought to the Romans he taught them and they believed Jesus was the Messiah. Therefore the Kingdom was given to the Romans. That is recorded in the New Testament.
What does the bible say about the tree grafting. Jack you need to go back and study the New Testament so you can understand correctly what is going on and who the Scriptural Nation of Israel related to God is now. Read this:
Romans 11:11-24 ESV;NKJV - Gentiles Grafted In - So I ask, did - Bible Gateway
Gentiles Grafted In
11 So I ask, did they stumble in order that they might fall? By no means! Rather, through their trespass salvation has come to the Gentiles, so as to make Israel jealous. 12 Now if their trespass means riches for the world, and if their failure means riches for the Gentiles, how much more will their full inclusion mean!
13 Now I am speaking to you Gentiles. Inasmuch then as I am an apostle to the Gentiles, I magnify my ministry 14 in order somehow to make my fellow Jews jealous, and thus save some of them. 15 For if their rejection means the reconciliation of the world, what will their acceptance mean but life from the dead? 16 If the dough offered as firstfruits is holy, so is the whole lump, and if the root is holy, so are the branches.
17 But if some of the branches were broken off, and you, although a wild olive shoot, were grafted in among the others and now share in the nourishing root of the olive tree, 18 do not be arrogant toward the branches. If you are, remember it is not you who support the root, but the root that supports you. 19 Then you will say, “Branches were broken off so that I might be grafted in.” 20 That is true. They were broken off because of their unbelief, but you stand fast through faith. So do not become proud, but fear. 21 For if God did not spare the natural branches, neither will he spare you. 22 Note then the kindness and the severity of God: severity toward those who have fallen, but God's kindness to you, provided you continue in his kindness. Otherwise you too will be cut off. 23 And even they, if they do not continue in their unbelief, will be grafted in, for God has the power to graft them in again. 24 For if you were cut from what is by nature a wild olive tree, and grafted, contrary to nature, into a cultivated olive tree, how much more will these, the natural branches, be grafted back into their own olive tree.
Israel’s Rejection Not Final
11 I say then, have they stumbled that they should fall? Certainly not! But through their fall, to provoke them to jealousy, salvation
has come to the Gentiles. 12 Now if their fall
is riches for the world, and their failure riches for the Gentiles, how much more their fullness!
13 For I speak to you Gentiles; inasmuch as I am an apostle to the Gentiles, I magnify my ministry, 14 if by any means I may provoke to jealousy
those who are my flesh and save some of them. 15 For if their being cast away
is the reconciling of the world, what
will their acceptance
be but life from the dead?
16 For if the firstfruit
is holy, the lump
is also
holy; and if the root
is holy, so
are the branches. 17 And if some of the branches were broken off, and you, being a wild olive tree, were grafted in among them, and with them became a partaker of the root and [
c]fatness of the olive tree, 18 do not boast against the branches. But if you do boast,
remember that you do not support the root, but the root
supports you.
19 You will say then, “Branches were broken off that I might be grafted in.” 20 Well
said. Because of unbelief they were broken off, and you stand by faith. Do not be haughty, but fear. 21 For if God did not spare the natural branches, He may not spare you either. 22 Therefore consider the goodness and severity of God: on those who fell, severity; but toward you, goodness, if you continue in
His goodness. Otherwise you also will be cut off. 23 And they also, if they do not continue in unbelief, will be grafted in, for God is able to graft them in again. 24 For if you were cut out of the olive tree which is wild by nature, and were grafted contrary to nature into a cultivated olive tree, how much more will these, who
are natural
branches, be grafted into their own olive tree?