How can Zionist take a tribe of Judah and form a Religion out of it when it was one tribe among eleven others?

If Judaism is a the true Religion of the ancient Hebrews. Then why is their no such thing as Levitism or Gadism. It seems to me that Zionist are misinterpreting what the word Jew means. All it meant was that you were a descendant of a tribal people known as Judah it never represented some mainstream Religion. Yahweh blessed Jacob with 12 sons and never in any scriptures of the Old Testament did they speak about Judah becoming a mainstream Religion. So one is not telling the TRUTH. It seems to me that their is a people in modern Israel claiming to be a people that they really aren't based on corrupt their false allegations of thier Judaism history.