The erev rav have been at the center of much of Israel’s problems. The issues began at Mt. Sinai with the golden calf, continued on to the time of Yeshua and exist to this very day.
Rabbi Yehuda said:
“Deceivers, get away from the deceivers, so that you will not befriend yourself with their acts, and then be part of their sins. Come and see: If there was no Erev Rav, those that united with Israel, that act (ie, making the Golden Calf) would not have been done, and all those who died from Israel would not have died, and all that was caused upon Israel would not have been caused. And come and see that act and that sin indeed caused exile for Israel…”
“Now that act was done, it caused everything, it caused the yoke of other nations, it caused that those tablets were broken, it caused a few thousand to die among Israel, and all this because of associating with the Erev Rav that went along with them.”
Rabbi Yitzhak explains that Psalm 37 is talking all about the Erev Rav:
“Rabbi Yitzhak opened and said (Psalms 37:1) “Do not pay attention to the deceivers (mereim)”. Who are the ‘deceivers’? For it is not written sinners or evildoers, but deceivers, for they deceive themselves, and those who befriend them.”
It is taught that the erev rav are responsible for the destruction of the Beit HaMikdash (Temple).
The Gaon of Vilna explains:
“All the exile, the destruction of the Temple and all the troubles – it all results from Moshe Rabbeinu having accepted the `erev rav. All the bold-faced and wicked people of the generation are from them, i.e., their souls are theirs (that is to say this is not physically inherited by lineage, but rather a mere reincarnation of souls), in that they are a reincarnation of them. This is what was meant in the Gemara, hani me`erev rav qa’ati – these spring from the erev rav” (Rabbi Yitzhak Hotner also commented on this, in “Pahad Yitzhak”, Pesah, pp. 246-247.)
Rabbi Chaim Vital, the main student of the Arizal, states in the introduction to his book Etz Chaim that the erev rav pursue ‘honorable’ positions in the Jewish religious world, and make a point of doing mitzvot in order to receive acknowledgement from others.
“All those that do kindness and toil in the Torah, all they do for themselves. And in particular through our many sins, in our times the Torah has been made into a hammer with which to do their own ends for many baalei Torah, who occupy themselves in the Torah in order to receive their reward and other benefits and luxuries, and in order to be in the group of heads of yeshivot, and judges in their courts, so that their names and fame spread throughout the land.”
The Gaon also describes the erev rav as carnal and corrupt thieves in honored positions:
“Of the Amalekites some were leaders of the Israelites in their galut, their exile, acting violently and robbing the Jewish poor, and they are from the side of the generation of the Flood… and the bad separated out in the `erev rav… and this is the fourth exile… They are the fallen ones, who follow around after loose women and after bribes of this world. They are warriors, men of great name, all of whose deeds are done in order to enhance their reputation. They are spirits who do not desire to bestow kindness and charity for masters of Torah; they are giants who ridicule Torah scholars” – Tikkunei Zohar, p. 194.
 Zohar II, 45b
 The Gaon on Tikkunei HaZohar 97, beginning v’aleihu.