I have long observed that in any group or movement, there comes a time when the balance shifts to the extremists in the group. I have witnessed many occasions myself when I am in a meeting and someone expresses an extreme position with passion. I look around the room, and I see uncomfortable looks on faces denoting "I am not comfortable with this. It goes too far for me, but I don't want to speak up and bring that passion down on me." I have frequently looked into my own soul at such a time and had the same response.
I think we saw it in the last decade in the Republican party, and in the previous decade in the Democratic party. The passionate minority becomes the voice of the organization, and they sweep everyone along in their fervor. Eventually, enough people start saying, "You know, this really isn't right," and the pendulum begins to swing back again.
Historically, there have been several such moments in American religion. The most famous of these are called "the Great Awakenings," which pushed an extreme version of Christian thought on America for what eventually turned out to be brief time periods. The First Great Awakening (1700's) is most famous for producing the Fire and Brimstone preacher Jonathan Edwards. Look up his most famous sermon, "Sinners in the Hands of an Angry God" for a sample of the theology involved there. The second Great Awakening took place in the 1820's, and its excesses spawned a powerful counter-movement that included the new version of the Unitarian church and the transcendentalist movement, with Ralph Waldo Emerson and Henry David Thoreau.
Another Great Awakening came later, and it produced the anti-evolution movement that led to the famous Scopes trial in Tennessee. That movement, too, died out.
My guess is that in another hundred years, historians will be referring to another such time period in this decade.