Many texts, publications, teachers, preachers etc. refer to ALL of Israel as Jewish. I'm forgoing putting links herein as there are many references online quickly and easily found. For example, "The 144,000 Jews of Revelation" as if all tribes are Jewish. But, far more than that. Some go as far as to say Abraham, Isaac and Jacob are Jewish. And, teaching and prophetic interpretations abound with the assumption all of Israel is Jewish.
How can this be defended using scripture?
Scripture shows Abraham, Isaac and Jacob were Hebrew. From Jacob, renamed Israel, on down all are "Israelites". But, ONLY the tribe of Judah (mixed with Benjamin and some Levites) are "of Judah" aka Jewish.
It isn't a trivial distinction. To properly identify who's being addressed to prophesies unto the end of this age, the understanding is quite different which side of this matter one views as who is Jewish with respect to Israel.