John S said in post 12:
The Jews are ONE Tribe of Israel - Judah - the ONLY Tribe that would maintain its identity.
Note that Jews include individuals from tribes of Israel other than Judah. For Paul is truly a Jew (Acts 22:3), and he's of the tribe of Benjamin (Romans 11:1). Indeed, Jews include individuals from all 12 of Israel's tribes, for there are no lost tribes, insofar as the 10 northern tribes weren't entirely lost to history. In 722 BC, the northern kingdom of Israel fell and its individuals were taken into captivity into Assyria (2 Kings 18:11), never to return to the land of Israel. They and their descendants were lost to history. But the 10 northern tribes in themselves weren't lost to history. For some 200 years before the captivity of the northern kingdom, when it first become idolatrous, some individuals from all 10 of the northern tribes left the northern kingdom to become part of the southern kingdom of Judah (2 Chronicles 11:16-17), and so by definition they all became Jews. That's why later the Jews living in the 1st century AD could be referred to as including all 12 tribes (Acts 26:7, James 1:1), and why at that time Anna could be said to be of the northern tribe of Asher (Luke 2:36), one of the so-called "lost" tribes.
So the people alive today who are descended genetically from a 1st century AD Jew would include individuals from all 12 tribes. Some of these descendants could know that they're Jews because their individual ancestors over the last 2,000 years kept their Jewish identity and didn't intermarry with Gentiles. But others of these descendants could know themselves only as Gentiles because their individual ancestors over the last 2,000 years eventually abandoned their Jewish identity and intermarried freely with Gentiles, to the point where their descendants alive today are almost entirely Gentile genetically. Similarly, regarding the individuals of the northern kingdom of Israel who were lost to history at its captivity, over the past 2,700 years, their descendants must have eventually abandoned their Israelite identity and freely intermarried with Gentiles, to the point where their descendants alive today would know themselves only as Gentiles, and would be almost entirely Gentile genetically.
--
Also, while God knows which people alive today are descended from one of the 12 sons of Jacob/Israel from whom the 12 genetic tribes arose (Genesis 49:28), nonelect Israelites/Jews aren't considered by God to be truly Israel (Romans 9:6-11) or truly Jews (Revelation 2:9b, Revelation 3:9), or God's children or Abraham's children, but the children of the devil (John 8:39-47), just as all the nonelect, no matter whether they're Jews or Gentiles, are considered by God to be the children of the devil (Matthew 13:38-39).
Some genetic Israelites are believers, and so are members of the church (Ephesians 4:4-6) and Israel at the same time, just as, for example, the genetic Jew Paul (Acts 22:3) is a member of the church and Israel at the same time (Romans 11:1). And some still-living, non-believing genetic Israelites are still considered by God to be Israel insofar as they're elect (Romans 11:25,28). All the still-living, elect, non-believing genetic Israelites who don't become believers before Jesus' 2nd coming will become believers (and so will become members of the church: Ephesians 4:4-6) at the 2nd coming (Romans 11:26), when they see the returned Jesus in person (Zechariah 12:10-14). But even though all those still-living, elect, genetic Israelites will eventually become believers and be saved, they will be only a remnant of all genetic Israelites (Romans 9:27), most of whom will never be saved, just as most of humanity in general, both Jews and Gentiles, will never be saved (Matthew 7:14, Matthew 22:14).
John S said in post 12:
God promised Abraham that his descendants would be as the sand of the sea and God keeps His promises.
Amen.
God indeed promised a figurative "I will multiply thy seed as the stars of the heaven, and as the sand which is upon the sea shore" (Genesis 22:17). But this was already fulfilled by only about 6 million Israelites at the time of the Exodus (Deuteronomy 1:10). And so Romans 9:27 and Isaiah 10:22 can refer to only a remnant being saved out of a few million people.
Christians are not back fitted into the 12 tribes. If you are not a blood descent of Jacob, and your mother is not a Jew, you are not of any of the twelve tribes. 
