In Christian thought, Paul explained that one need only be "adopted" by faith in Christ, Israel's king, to become an Israelite.
But in terms of Old Testament thinking, how could one become an Israelite?
There were uncircumcised gentiles in Old Testament times who had faith in and worshiped Israel's God. This group is sometimes called "Noahides", because they followed the rules from Noah's time, before Moses. Would they count?
What about other people who lived under Israelite rule and had faith in Israel's God, but still did not follow the Mosaic laws?
Aren't there cases of gentiles, perhaps like Ruth or Rahab, who were also considered Israelites based on one of the above criteria?
Finally, St Paul wrote that God "endured... the vessels of wrath... that He might make known the riches of His glory on the vessels of mercy, ...even us whom He called, not of the Jews only, but also of the Gentiles".(Romans 9) Paul then goes on to cite Hosea's prophecy about the Israelites in the New Testament being called "not my people" by God and then being called God's people again. Hosea was talking about the dispersement of Israel under the Assyrians.
Then in Ephesians, Paul said that since he is from the tribe of Benjamin, he is proof that God hasn't forgotten his people. This refers to the fact that God dispersed the tribe of Benjamin in Hosea's era. Perhaps at that point the Israelites became gentiles shortly, as Hosea wrote that the gentiles swallowed Israel up.
Does St Paul's discussion of the story in Hosea of the people losing their Israelite identity and getting it back show that God called not just the Jews, but the gentiles to be His people?