I found this forum while searching for Google for info (actually, I was looking for a listing of which denominations are considered mainline). Sorry if I’m replying to a topic that is over a month old.
Anyways, this is what I can say about divisions of Protestantism as covered in social science research. Keep in mind that social science definitions of what a person’s religion is depends on how the person self-identifies. Theologically, some religious groups will be more exclusive. Orthodox Jews won’t necessarily believe that practitioners of Reform Judaism are all Jews, for example.
In the beginning of survey research, Christians were generally divided into Catholics and Protestants (and other). Over time, social scientists have divided Protestants into mainline and evangelical. In papers and books from the past ten years or so, I’ve noticed a new trend of separating out a third group of Protestants: charismatic Christians.
Generally, the mainline churches are Episcopalian, Presbyterian, Methodist, Lutheran, American Baptist, United Church of Christ, and Disciples of Christ. The stereotype is that they are denominations that were mostly strong during the birth of the nation. They are often described as liberal and, politically, their members are left-of-center. (Evangelical Christians are decidedly right-of-center and Catholics are somewhere in the middle.)