Is Satan evil?

[EGross]

 The word Lucifer is taken from the Latin Vulgate,[2] which translates הֵילֵל as lucifer,[3][4] meaning "the morning star, the planet Venus" (or, as an adjective, "light-bringing").[5] The Septuagint renders הֵילֵל in Greek as ἑωσφόρος[6][7] (heōsphoros),[8][9][10] a name, literally "bringer of dawn", for the morning star.[11] Kaufmann Kohler says that the Greek Septuagint translation is "Phosphoros".[2]

Yes, the Christians read Isaiah 14:12 (the only place it exists as a proper noun):
[quote="KJV"]Isa 14:12 How art thou fallen from heaven, O Lucifer, son of the morning! how art thou cut down to the ground, which didst weaken the nations!

So they can get a fallen angel from that. I prefer this translation (my own):

How have you fallen from the heavens, Lucifer (Venus), son of the morning, who has been cut off, [falling] to the Earth, controlling the nations (goyim)?"

(There is a theological belief that this represented the fall of the Babylonian kingdom, which was the rising star (morning), until the fall of that kingdom. But since the word "Gehinnom" appears multiple times, and they wrongly equate this as "Hell", well, Lucifer and a lot of hell makes for a nice story.)