Christians will back the 12 Tribes of Israel because they’re the foundation of their religion. You can’t have Christianity without accepting God chose the Jews as his people and created the Kingdom of God and distributed it amongst Jacob’s 12 sons. If this is not true, nothing after it is either including Jesus as the Son of God, gentiles being accepted, and being judged be the 12 thrones in End Times.
This is demonstrably wrong. If you want to argue that Christians are hypocrites then fine. But the mere existence of that story doesn’t create an obligation and most Christians don’t even connect that to modern Israel.