What is the theme of 'The Hunchback Of Notre-Dame'?

It is a romance tragedy involving rejected love, corruption of the church, two befriended outcasts, and unvanquished passion which may drive all of paris to fire. This story has no happy ending, only in death of the two outcasts is there some resemblance of resolve. 'Tis a play upon wickedness that goes unnoticed and desire that is not returned.