No event in American history which was so improbable at the time has seemed so inevitable in retrospect as the American Revolution. On the inevitability side, it is true there were voices back then urging prospective patriots to regard American independence as an early version of manifest destiny. :)
One of the results of the Enlightenment was that people began to think for themselves. This resulted in many people questioning the absolute authority they were used to living under. People no longer believed that kings ruled by divine right.
Because they exercise a manner or resemblance of divine power on earth