Israel of God

Israel of God (Greek) Ἰσραὴλ τοῦ θεοῦ occurs only once in Scripture. The apostle Paul used the expression to show that the "Israel of God" has nothing to do with whether one is a circumcised descendant of Abraham or not (Galations 6:15, 16 (NIV), compare Matthew 3:9). Paul referred to the Hebrew prophet, Hosea, where God (Jehovah) said: “I will call them ‘my people’ who are not my people; and I will call her ‘my loved one’ who is not my loved one,” (Romans 9:22-25 (NIV); compare Hosea 2:23) to show that God would extend his promise to Abraham to a spiritual nation (Matthew 21:43 (NKJV)), which includes some natural Jews and "the Gentiles".

Tribe of Israel
c. In 96 CE, apostle John witnesses in a vision, the things Paul had earlier taught the congregations, regarding God extending his kingdom arrangement to "non-Jews" (more importantly non-descendants of Abraham): "And I heard how many were marked with the seal of God —144,000 were sealed from all the tribes of Israel" (Revelation 7:4 (NLT)). Comparatively, apostle John's list of "all the tribes of Israel" in his vision, do not completely match the descendant list of natural Israel given in Numbers chapter 1. John further describes in his vision that before him was "the Lamb, standing on Mount Zion, and with him 144,000 who had his name and his Father’s name written on their foreheads" (Revelation 14:1 (NIV)) and "they were purchased from among mankind." (Revelation 14:4 (NIV)).

Jehovah's Witnesses
Out of ≈8,000,000 (million) Jehovah's Witnesses, only an estimated few thousand alive today, identify with the 144,000 servants, of the spiritual tribe of Israel, who earnestly await to receive the "seal on the foreheads" —Rev.7:3 (NIV) and have "the Lamb's name and his Father’s name written on their foreheads"—Rev.14:1 (NIV).