This expression, found only once in Scripture, refers to spiritual Israel rather than to racial descendants of Jacob, whose name was changed to Israel. (Ge 32:22-28) The Bible speaks of “Israel in a fleshly way” (1Co 10:18), as well as spiritual Israel made up of those for whom descent from Abraham is not a requirement. (Mt 3:9) The apostle Paul, when using the expression “the Israel of God,” shows that it has nothing to do with whether one is a circumcised descendant of Abraham or not.​—Ga 6:15, 16.

The prophet Hosea foretold that God, in rejecting the nation of natural Israel in favor of this spiritual nation, which includes Gentiles, would say “to those not my people: ‘You are my people.’” (Ho 2:23; Ro 9:22-25) In due time the Kingdom of God was taken away from the nation of natural Jews and given to a spiritual nation bringing forth Kingdom fruitage. (Mt 21:43) To be sure, natural Jews were included in spiritual Israel. The apostles and others who received holy spirit at Pentecost in 33 C.E. (about 120), those added on that day (about 3,000), and those that later increased the number of the men alone to about 5,000 were all Jews and proselytes. (Ac 1:13-15; 2:41; 4:4) But even at that, they were, as Isaiah described them, “a mere remnant” saved out of that cast-off nation.​—Isa 10:21, 22; Ro 9:27.

Other scriptures elaborate on this matter. With the breaking off of some “natural branches” of the figurative olive tree, there was a grafting in of “wild” non-Israelite ones, so that there was no racial or class distinction among those that “are really Abraham’s seed, heirs with reference to a promise.” (Ro 11:17-24; Ga 3:28, 29) “Not all who spring from Israel are really ‘Israel.’” “For he is not a Jew who is one on the outside, nor is circumcision that which is on the outside upon the flesh. But he is a Jew who is one on the inside, and his circumcision is that of the heart by spirit.” (Ro 9:6; 2:28, 29) Natural Israel failed to produce the required number, so God “turned his attention to the nations to take out of them a people for his name” (Ac 15:14), concerning whom it was said, “You were once not a people, but are now God’s people.” (1Pe 2:10) The apostle Peter quoted what had been said to natural Israel and applied it to this spiritual Israel of God, saying it is in reality “a chosen race, a royal priesthood, a holy nation, a people for special possession.”​—Ex 19:5, 6; 1Pe 2:9.

The 12 tribes mentioned in Revelation chapter 7 must refer to this spiritual Israel for several valid reasons. The listing does not match that of natural Israel at Numbers chapter 1. Also Jerusalem’s temple and priesthood and all the tribal records of natural Israel were permanently destroyed, lost forever, long before John had his vision in 96 C.E. But more important, John received his vision upon a background of the aforementioned developments from and after Pentecost 33 C.E. In the light of such events, John’s vision of those standing on the heavenly Mount Zion with the Lamb (whom natural Israel had rejected) revealed the number of this spiritual Israel of God to be 144,000 “bought from among mankind.”​—Re 7:4; 14:1, 4.