Jesus was talking about a seed line when he said this:

Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.

Not everyone who says they are of the tribes, is- and many of the true tribes are known as "Christian" now, because of Jesus and the apostles. The heard the Word and believed. Wheat and chaff, gold and dross, wheat and tares...multiple layers to identify a people and the faithful.