Last Sunday, as I was writing this week's 512 story, I casually mentioned on Twitter that I was "researching the difference between the Devil, Satan, and Lucifer." Lo and behold, @GrammarGirl saw that and said she would be interested in my findings. So here they are, in brief:
In a modern Judeo-Christian context, there's really no practical difference between "the Devil," "Satan," and "Lucifer." (Note that the capital "D" is important in the first term; lowercase-"d" devils can refer to a number of things, from vacuum cleaners to zombies.) The interesting thing is how those terms originated, and how they came to be conflated.
Let's start with Lucifer. It comes from the Latin LUCEM FERRE, which means, literally, "light-bringer"--the term originally referred to the planet Venus ("morning star"), which is often visible at dawn. It wasn't until later that the name Lucifer became synonymous with a supernatural being who presides over Hell and tempts humanity to commit sin. (In fact, in Revelation 22:16, Jesus refers to himself as "the morning star"--though he uses different words, not "Lucifer.") John Milton popularized the notion in Paradise Lost when he made "Satan" and "Lucifer" the same character, drawing a distinction between the wayward angel's post- and pre-fall-from-Heaven names.
(Aside: DC Comics, by way of Vertigo's Sandman series, gave him a full name--"Lucifer Morningstar"--which is a bit redundant, but I like the implication that he has a family, and maybe relatives he doesn't like so much. More on that below.)
Satan, on the other hand, derives from the Hebrew term ha-Satan, traditionally translated as "the adversary" and with the definite article prefix indicating a title rather than a personal name. I'm not a Biblical scholar (I rarely touch the stuff), but as far as I can tell, the earliest Greek translation of the good book turned satan into the Greek word diabolos ("slanderer") in some places but not others, possibly causing confusion about whether the Hebrew word was a proper name. Many mythological creatures and persons are called by multiple names anyway, so it's not a stretch to think that readers just went with it.
Finally, the word Devil comes--as you might imagine--directly from the Greek diabolos, but depending on who you ask, the term may refer to either a demon or a fallen angel or simply a symbolic figure representing evil and/or temptation. It's the most generic of the three terms presented here, always used as a title rather than a personal name; that probably explains why it's the most versatile and most often abused.
In my flash fiction piece "One of Our Angels is Missing," I go with the modern interpretation and use all three of these terms interchangeably. I have a little fun with the name Lucifer, which of course abbreviates to "Lou," and introduce the Devil's twin brother as my protagonist. (No, this is not based on any existing mythology I know of; I enjoy making stuff up.) Stanley Morningstar may be a bit slow, but he's basically a nice guy. Well, as nice as you can be when you live in Hell...
Read "One of Our Angels is Missing" at 512 Words or Fewer