A book is called Son of God or Son of the Devil. Why God is without “the” while Devil is with it? Should it be like that traditionally or there is some special meaning if put this way?
Is not it a bit strange: God is a name of a god?
Those who believe in only one god refer to him and address him as God. I suppose it's not really a 'name', more a combination of name and title.
If you used a name, you could omit the:
Son of God or Son of Satan