The F-word x 3
If you prefer your definitions extremely literal—like, well, a fundamentalist—then, yes, fundamentalism has a historical-theological meaning tied originally to a movement in American Protestant Christianity. The Baptist theologian Roger E. Olson is a knowledgeable guide if you care to take up that journey.
Recently, however, I've come across three broader descriptions of fundamentalism that I've found quite helpful, especially as we think about it in the context of pronounced globalization. I think these descriptions open up a larger vista from which to see the fundamentalist mood, generally speaking, socially speaking.
And perhaps a sociological understanding of the F-word is ultimately more useful: first, in checking ourselves—and our faith or social movement—in the mirror; then, in countering the rhetoric and activity of fundamentalism in the societies we inhabit.
#1. Do you (absolutely) refuse to live in tension?
The growth of multiculturalism and globalization brings us rising levels of complexity and nuance. The ability to hold tension is absolutely essential. Fundamentalism—strict adherence to one's view of the world as the only right way—is essentially a refusal to live in tension.
author of The Cultural Intelligence Difference
#2. Do you demonize the other (and, secretly or not-so-secretly, want to hurt or harm the other), but to you it just feels like passion for the truth as you understand it?
All fundamentalisms [share] an obsession with a single truth as understood by me or my group, the demonizing of others who refuse to get behind this "truth," [and] the willingness—even desperation—to destroy those who offer alternatives...
Professor of Islamic Studies, University of Johannesburg
#3. Do you think very highly of religious faith mostly because it provides an opportunity to get what really matters in life: your politics?
Fundamentalism, in all our faith traditions, is a politicized use of religion based on fear and power.