Rabbi Yaakov Teitelbaum related that his grandfather heard Rabbi Yisroel of Ryzhin say over 150 years ago: "Jews, you must know that before the coming of moshiach, a fire will come down from heaven like the fire that came down for Eliyahu Hanavi on Mount Carmel (I Kings 18:38). But there will be a big difference: then the fire came down for Eliyahu Hanavi, but in the future before the coming of moshiach, it will come down for the prophets of the Baal. And Jews will have to climb up sheer walls to remain with their faith."
Rabbi Yisroel of Ryzhin continued: The only solution for a Jew to stay safe from heresy at that time will be to stick together with other believing Jews. This is what Yaakov Avinu told his children, “Gather together and I will tell you what will happen to you in the end of days.” The word “happen” could also be translated as “cold”, just as we find in the words “asher karcha baderech” (Devarim 25:18) which Rashi translates as “he [Amalek] made it cold for you on the way.” In the end of days, when Amalek tries with all his might to “cool off” the Jewish people and lead them astray from their faith, the only road to safety is to gather together and discuss the true emunah. (Kol Yaakov pp. 81-82)