What do we learn from "Pachadu v'Tziyon Chata'im"?
Brachos 60a: One who fears is called a sinner. "Ashrei Adam Mefached Tamid" (Mishlei 28:14) refers to Divrei Torah (lest he forget).
Bereishis Rabah 48:6: This is a parable for two children who fled school. One of them was lashed, and the other feared.
Rashi: They feared, how will they find an opening for Teshuvah?
Radak, Malbim: The sinners [and flatterers] in Tziyon feared when they saw the great Machaneh Ashur. They did not trust in Hashem.
Who are "Chanefim"?
Bereishis Rabah 48:6: This always refers to heretics 1 .
Radak: They are Shevna and his entourage.
Malbim: They are insincere people, who are ashamed to say that they fear and do not believe in Hashem. Even so, all recognized their fear via their trembling.
Nezer ha'Kodesh (on the Midrash): It already says that sinners will fear; flatterers are included! Why will Chanefim fear more? We must say that this refers to heretics.
Why does it say "Mi Yagur Lanu Esh Ochelah"?
Rashi #1: Who will stand for us to assuage burning anger?
Rashi #2: Who will live in Tziyon with the Rock, who is a consuming fire? The next verse answers this - one who goes in [the way of] Tzedakos.
Radak, Malbim: Who will stand for us against this camp, which is a consuming fire? The sinners said so; Chizkiyah and his entourage knew that Hashem will save them when they repent, scream and pray to him.
Radak citing Targum Yonasan: Who will dwell for is in Tziyon, in which is the radiance of the Shechinah, like a consuming fire?
Who are "Mokedei Olam"?
Malbim: They already burned the majority of the settled land. (How can we live and trust in Tziyon?!)