Satan was one of God's highest ranking angels, like Uriel, Raphael,
Michael, and Gabriel.  In fact, his name was Satanel.  He did challenge
God's authority and got kicked out of heaven.  A lot of the mythology
of Satan (he lost the -el suffix when he fell) comes from the
Book of Enoch and is not found in the bible.

Read the Book of Enoch, available thru bookstores, or get the book
called "Angels: an endangered species" (I think).

