Heh, I don't really want to become embroiled in a religious debate, mind you, but I guess I ought to clarify a thing or two about my position and those that share it, whoever they may be.
As you read this, please note that I cannot change your mind. I can only present to you what I believe to be true, so that you may consider/understand it. That is, you are the only one that can change your mind.
Also, in general, please keep in mind that something above our realm of understanding is not necessarily contrary to it. Our language is limited, and so is our capacity for understanding.
As has been stated before, God created man and angels with free will. (This is one of those "givens" which I cannot convince you to believe if you firmly believe otherwise... though you can accept it if you would like - regardless, debating against it will likely lead to nobody changing anybody's mind.)
Why did God create man and angels with free will? God knows. I don't. Perhaps, free will is a part of God's image, in which He created us, as a reflection of His love. Perhaps it is better that we have free will, so that we can choose to follow God, or choose otherwise. Given that God is all-good, we can assume that He did it for some overall good reason. God knows what is best much better (infinitely better, in fact) than I do. That is, perhaps it's a greater sign of love to give somebody free will and have him reject you, than to not give him the choice at all. Maybe all the bad consequences of our God-given free will are infinitely overcome by the good consequences.
It's a gift, and we can do what we want with it, in any case.
So, Lucifer chose not to follow God. Why?
We don't really know, but we can speculate. That is, some speculate that at some time, God told all the angels that the His Son - the second person of the Trinity, or, the Word, if you will - would take on man's nature in addition to His divine nature. As a result, the angels would have to worship and obey a man (that is, a person who is both fully God and fully man) in their worship and obedience of God. Lucifer refused to bow to this man-God person, and chose to separate himself from God, making himself the enemy of God. But that's speculation, and I wrote it because I found it kind of interesting to ponder/consider.
So, for whatever reason, Lucifer rejected God and separated himself from Him, becoming an enemy of God: Satan. As such, entered a place void of God: Hell.
We can choose to seek God, the truth, and everything ourselves. Likewise, we can choose against it. Yes, God is outside of time, in eternity (an "ever present now," as they say... not contrary to logic, but not fully comprehendible, it seems). In eternity, He knows everything, before, during, and after it happens.
One good thing to remember is that just because Sam somehow knows farmer Bob will throw three sticks to a dog before farmer Bob throws them, farmer Bob is still the one making the choice to throw the sticks. Likewise, just because God knows you're going to choose to go to Heaven/Hell, you are still the one choosing to go to Heaven/Hell.
But, justice is a good thing, and since God is all-good, He is all-just. As such, I believe that we get what we put on our plates, ultimately. What it comes down to is that Heaven or Hell is your own choice, and if you don't deserve Hell, you won't get it. It's believed by some that those in Hell would reject God for the rest of eternity, and that they won't want Heaven, or God, despite all the extreme "warmth" of their surroundings.
(And yes, that was a joke, in reference to Meisel's first post.)
What follows is that I believe that we are the ones sorting ourselves out, not God. It is not my place to say that God should change the world into something better than it already is; He knows what is best - not I - and what is best will ultimately happen.
Please don't debate or argue against these statements. Saying "I disagree" would be fine, but saying "you're wrong" would be pointless, as we all know nobody will change anyone's mind about religion on a piano forum. This post was not made as an attack against anybody - it is a posting of what I believe on the matter, as was requested by Meisel, originally. (I don't think I would have the time to debate in at least the next week or so anyway, since I'm leaving MD for college in Spain, and I have little clue as to what my internet/time situation will be.)
So, if you would like to learn more, it would be MUCH more fruitful to read some good books, on your own, to better educate yourself of the Christian position (if you do not want to learn more, then, well... I have nothing to say). One recommendation is the Summa Theologica, by Thomas Aquinas.
https://www.newadvent.org/summa/ seems to be a decent compilation of it... even if you're not Catholic or Christian, I would recommend it.
Also, this is not Christian and it will probably not answer the question "why is there evil", but I recommend you read Plato's dialogues (particularly the trial of Socrates), and listen to Professor Sugrue's commentary on it. Google Professor Sugrue and Plato, and you'll see what I'm talking about. You should be able to find it in public libraries. (Sugrue was a professor at Columbia University, then Princeton University, and he switched this year to Ave Maria University in Florida this year. A smart guy.) It's... a good thing to put stock in, especially if you shun anything Christian. I believe it's a good idea to actively search for what is truly and objectively good.
I hope all that was clear and unoffensive to everyone... I sincerely tried to make it both.
Topic: The purpose of Satan