In Proposition 64, George Peters states:
“The Kingdom being given to the elect only, any adoption into that elect portion must be revealed by express Divine Revelation.”
An inheritance is simply not given to anyone without the permission of the father. In the case of the engrafted elect, a path or process by which the inheritance and promises of the Kingdom could be extended must come from the King/Father. God had to provide a way for the adoption process to unfold and He did so through the blood of the Messiah. His blood was the signature on the adoption paperwork for the engrafted elect.
The most notable observation Peters presents in Proposition 64 is the following:
“This doctrine of the election of the Jewish nation, is one so clearly taught that it was deeply rooted in the minds of the Jews. The result was that no addition could be made to it or allowed without an extraordinary Divine revelation. Hence we read (Acts 11) that when “the apostles and brethren were in Judea heard that the Gentiles had also received the word of God,” they contended with Peter in consequence of his thus encouraging the Gentiles. Peter rehearsed the whole matter; what vision he had seen; what directions he had received; what results had followed; how God had acknowledged the validity of such an engrafting of Gentile believers by the bestowal of the gifts of the Holy Ghost. This was satisfactory; for “when they heard these things, they held their peace, and glorified God, saying: Then hath God also to the Gentiles granted repentance unto life.” On a later occasion when the dispute was again raised by a few respecting the conversion of the Gentiles under Paul and Barnabas, Peter interfered, showing how the Gentiles through him heard the Gospel and believed, the Holy Ghost testifying to the same. Then Paul and Barnabas increased the force of the testimony by relating what miracles and wonders God had wrought among the Gentiles through them. The result of the discussion is announced by James (Acts 15:13-21), in which we have distinctively three things presented: (1) The election and incorporation of the Gentiles, “Simeon hath declared how God at the first did visit the Gentiles, to take out of them a people for His name;” (2) the identification of this elect people with them (the Jews) in the covenanted Kingdom, “And to this agree the words of the prophets, as it is written, ‘after this’ (viz.: after this people are gathered out) ‘I will return and will build again the tabernacle of David, which is fallen down; and I will build again the ruins thereof, and I will set it up,'” – both elect enjoying this restored Theocratic-Davidic Kingdom; (3) the blessings that would follow this restoration, “that the residue of men,” etc.”
The Jews understood the nature of their election as being from God. He chose a people to be His from all other nations. Any addition to the family if you will had to take place within the parameters set forth by the Father, the One who does the electing. It is thus not surprising to see the response of the Jews to the preaching of the message of the Kingdom to the Gentiles. It truly had to be a defined and demonstrable act of God for the Gentiles to be grafted into the promises of the Kingdom. When Peter, Paul, and Barnabas relayed what God had done, the Jews (at least those who understood what God was up to), realized the promises to Abraham were being fulfilled. God was grafting in the Gentiles to the root and we see the Jews greatly rejoicing and glorifying God that the promise of life and adoption had been extended and accepted by the Gentiles.