What is the Chidush that they did not fear Hashem?
Rashi: Even though Nochrim serve idolatry, they fear Hashem and call him the G-d of gods 1 - "u'Shmi Nora va'Goyim" (Mal'achi 1:14). These people did not fear Him. They said, if He has [Power] to be feared, He would not have let His nation be exiled!
Malbim: They serve images to be an intermediary between the First cause (Creator) and people.
Why were the lions killing them?
Malbim: As long as Nochrim acknowledge the First cause and serve images only to be an intermediary, this is not such a sin, for they are under the Ma'arachah (influence of the stars). When they cease to have any fear of Hashem, they lose their human form and [therefore lose] the fear [of people] that is upon animals 1 .
Lions are Mu'ad (Bava Kama 1:4). They are prone to kill all people, except for great Tzadikim! This is when they are hungry. They do not kill without need. However, they killed Kusim without need, for they lost their human form. However, Malbim (verse 25) said that they were eating the Kusim! This requires investigation. (PF)
