As opposed to Mormons--who do other Christians think Satan is?

I believe what the Bible says, satan (Lucifer) was God's most beautiful creation who decided he was equal with God and got other angels to follow him and God kicked all of them out of heaven. God has given Satan power on earth to try and deceive (which, by the way, Satan is successful in the task) God's people. All our members (body parts) are written in the Lamb's book of life before we are formed in our mother's belly, the trick is to not get it blotted out of the book.