Heavens knight

The world was once ruled by humans. But then the earth opened and demons took control. Satan became the high ruler. Some had thought god was lost. Or maybe he just didn't care. But after hundreds of years he showed his hand. He gave the world a white knight. who goes by the code given to him through the bible. God gifted him the power of the elements. But it is said that soon he shall have to defeat satan himself.
And to do so he will need the angel Michael's holy sword. Will he find it? Or will a different holy relic come into play?