Some thousand years ago, some evil little spirit decided he'd become a great god, maybe the greatest of all. So he convinced some desert nomads to worship him and no other god. When he had gained enough power (because he got fed with psychic energies by those Hebrew people), he talked some lesser gods into helping him.
With their help, he became greater and greater, and his human pets who called themselves Jews prospered. Then that crazy god, who had even been bold enough to tell his Jews that he had created the world, told those lesser gods they were to become his lackeys, his slaves, that they should do all the dirty work for him, praise him and sing for him.
Some of them said, »But YHVH, we helped you to become so great a god, shouldn't we have our share, too?«
The boldest among those gods who were called »angels« was a guy called Lucifer, and when YHVH told them they were meant to serve, he said, »Non serviam.«, which means »I will not serve.«
YHVH got angry and kicked him out of heaven. Lucifer was about to go anyway, but YHVH had to kick him out in order not to lose his reputation.
Lucifer has my sympathies, YHVH doesn't.