I'm currently reading The Rise of Evangelicalism, a 2004 work by Mark Noll that looks at evangelical history to about 1800. While I'm only about 70 pages in, Noll makes a few important arguments in this general overview of the movement. One of the arguments that is not really common in evangelical circles is the importance of High Church Anglicans in the movement. However, Noll points out that the parents of John and Charles Wesley were High Church Anglicans and that the more famous Wesleys attended Oxford to become Anglican ministers.
Noll points out a convergence of Puritan (dissenting Anglican), Pietist (German groups like the Moravians), and High Church Anglicans that led to the emergence of the Evangelical movement. Many who were concerned with a church hierarchy and a national church had a problem with the evangelicals. The early evangelicals tended to favor use of the Bible over tradition and a sort of lay piety that encouraged lay meetings on a regular basis. It is easy to see why an established church might have problems with this.
Two thoughts come to mind. 1) The clergy may have been worried about their place in society. 2) The clergy may have been worried about the new and unique doctrines that might arise in such an environment. The first concern did not really come to pass, at least in American church history. Religious sentiment actually increased after what Nathan Hatch referred to as the "Democratization of Religion." However, the second concern did, in fact, happen. The Second Great Awakening is widely considered the biggest revival in American church history. Some of the ministers were quite orthodox in their beliefs. It is important to note that some unorthodox and heretical groups came out of this movement. I'm interested to see the major figures that Noll notes in the rest of the book, as it is more of a general historical overview than a narrow look at one group or movement.