Why was the french revolution so bloody?

It seems to me as if somewhere along the road, these Enlightenment ideas were in a way corrupted. The killing of the King is understandable because he is a symbol of the old way of government. Even killing the highest, most elite of the government was understandable. But killing every last government associate and even priests seems like a very noticeable turn from the traditional Enlightenment philosophies of Jean-Jacques and Voltaire.

on february 25, 2004, at the time the president of united states of america george bush announced that he supports the constitutional amendment to ban the same-sex marriage. but the possibility was left that states can decide whether they allow civil unions.