American religion is heavily tied into a Protestant Ethic mindset. Most famously, Max Weber tied capitalism, the main economic system of the United States, to Protestant work ethic and values of frugality and industry. William Bradford, the Purtian governor of Massachusetts records that the system of communalism he originally tried did not work as men "had no more in division of victuals and clothes than he that was weak and not able to do a quarter the other could; this was thought injustice." The women thought "to be commanded to do service for other men, as dressing their meat, washing their clothes, etc., they deemed it a kind of slavery.." (Both quotes from William Bradford's Property, http://press-pubs.uchicago.edu/founders/documents/v1ch16s1.html). So when communalism failed, the capitalist system was tried and took root in the American Protestant mindset.

With this capitalist system, religion became affected by it. People followed preachers who they liked and left those who they didn't.People like Joseph Smith, Mary Baker Eddy, and others were the preachers successful, spurring new worldwide denominations. For every religion that succeeds in the marketplace of ideas, there are many who don't, like the Shakers. There are less than 10 Shakers in the United States today.

This is a cursory view, and I'm doing a thesis concerning religious individualism and Vatican II, so I can explain more from the Catholic point of view. I'm still free to answer any follow up questions.