Here We Shall Explain Exactly Why Jesus is not a Jew
What if Jesus were descended from the Israelite tribe of Judah, as the Scripture says that He is? Well, of course He is, because the Scriptures do not lie. But what if the people known as Jews today were NOT of the tribe of Judah? Then how could Jesus possibly be a Jew? The answer is easy, Jesus is not a Jew because the people known as Jews are not of Judah.
For this reason Jesus Himself told the church at Smyrna, in Revelation 2:9: "I know thy works, and tribulation, and poverty, (but thou art rich) and I know the blasphemy of them which say they are Jews, and are not, but are the synagogue of Satan."
Just in case that is not understood, Jesus Himself also said to the church at Philadelphia, in Revelation 3:9: "Behold, I will make them of the synagogue of Satan, which say they are Jews, and are not, but do lie; behold, I will make them to come and worship before thy feet, and to know that I have loved thee."
So according to Jesus Himself, the people calling themselves Jews are not "real" Jews, meaning that they are not actually of the tribe of Judah. But how can that be? First, we will see that Paul of Tarsus agrees with Jesus, and the events which Luke recorded in Acts chapter 26 were actually about 30 years before John recorded the Revelation.
In Acts chapter 26, as Paul addressed Herod Agrippa II, he spoke about the promise of the Gospel and he said: "6 And now I stand and am judged for the hope of the promise made of God unto our fathers: 7 Unto which promise our twelve tribes, instantly serving God day and night, hope to come. For which hope's sake, king Agrippa, I am accused of the Jews."
So according to Paul, the promises in Christ are for "our twelve tribes", meaning the twelve tribes of the children of Israel. But the Jews, whom Paul mentions as an entity distinct from the twelve tribes, were opposed to that promise, and therefore on account if it, they were making accusations against Paul.
To Paul of Tarsus, the twelve tribes are not "Jews", and the Jews are not the twelve tribes. That is why Paul had a Gospel message to the nations of Europe, but that is a different story entirely.
One place in the Bible where the confusion is cleared up a bit is in Romans chapter 9.