any scripture to support this, or are you going off commonly held assumptions?

a Jew who accepts Christ is still a Jew, according to the original meaning of that word.

the point is that God himself has pointed out that there is a group of evil people pretending to be Jews.

pretty obvious that's what we're dealing with these days. we were not meant to attribute their evil deeds to Jews in biblical times, nor are we today.

Fact: Revelation speaks of the 12 tribes of Israel.

Also Fact: Revelation hasn't happened yet.

Irrefutable Fact: If God speaks of the 12 tribes of Israel in Revelation, and Revelation hasn't happened yet, then Israel, all 12 tribes which are considered "Jews", are considered as existing at all times past and into the future.

Please read the bible more, you're embarrassing yourself.

Romans 11:25 I do not want you to be ignorant of this mystery, brothers and sisters, so that you may not be conceited: Israel has experienced a hardening in part until the full number of the Gentiles has come in, 26 and in this way all Israel will be saved. As it is written:

“The deliverer will come from Zion; he will turn godlessness away from Jacob. 27 And this is my covenant with them when I take away their sins.”

28 As far as the gospel is concerned, they are enemies for your sake; but as far as election is concerned, they are loved on account of the patriarchs, 29 for God’s gifts and his call are irrevocable. 30 Just as you who were at one time disobedient to God have now received mercy as a result of their disobedience, 31 so they too have now become disobedient in order that they too may now receive mercy as a result of God’s mercy to you. 32 For God has bound everyone over to disobedience so that he may have mercy on them all.