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.

These were people who had lived under a king and not being aristocrats, they had no sense of how to use their newly found power. As Lord Acton said, "Power corrupts and absolute power corrupts absolutely." They were deeply resentful of the king's negligence in providing for his own people. They had revenge on their minds and hate in their hearts. They saw the guillotine as justice not malice and seeing the aristocrats suffer as they had suffered gave them a certain satisfaction. The Catholic Church was the moral authority in France for centuries and Robespierre and his minions sought to do away with the Church so that there were no more moral restraints imposed on their behavior.