I've thought about the lucifer question a bit, and since you asked I'll say this in a way that should be entirely accurate from a Christian perspective.
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The only way to answer your questions about lucifer are through the grace of God. In other words, only those chosen by God somehow to experience Grace will Know, and everyone else will have to make do with answers from books or pastors or whatever. This means other people's answers will never be conclusive for you, and should you recieve the answers, your answers will not satisfy most other people.
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You cannot earn the Grace of God through actions. You have to be chosen.
So until God gives you the answer, which may not happen, you won't know for sure, and although I could suggest some answers from other traditions, you would still have doubts.
Also, for what it's worth, I will say that the answers from other traditions would only make you more uncomfortable about the entire thing, they most likely wouldn't make you happy unless you're a very open-minded sort of Christian, and that wouldn't be helping you at all. It would just be adding subtle anxiety.