So many Christians are liars, hypocrites, gossipers, etc. They're no better than anybody else. Moslems have told me that Islam believes in the Bible. They study the Bible. Catholicism teaches salvation by grace and good works, not by faith alone.
Many Protestant denominations have no theological differences.
As a result of sin, Lucifer became the most corrupt, most evil creature in existence. God drove Lucifer out of paradise. Satan corrupted his own wisdom. Although Satan's wisdom is now corrupt, he is still very wise. God punished Satan by bringing him to a terrible fate.