Religion (when it is real religion) helps form an active, mutual relationship between a person and the infinite reality in whom each person participates as a unique, divine spark.
Fundamentalism (which is misunderstood as extreme religion, but which is failure of religion) severs relationship with infinite reality and replaces in with beliefs. The entirety of Fundamentalism’s metaphysics — “god”, types of people, categories, moral judgment — takes place inside the skull of the “believer”. Its heaven is imagined and the god who riles over this imagined kingdom is the believer. I call this misapotheosis: stupid confusion of oneself with God and confusion of Creation with the paltry product of one’s own creative imagination.
Fundamentalism places all emphasis of the factual content of its belief, so it sees no connection between itself and other denominations of Fundamentalism. What could be more opposite, Christianism and Progressivism? But each approaches belief the same way and approaches non-believers the same way. The faith is identical, and the differing content is a superficial difference.
Recovering “Christian” Fundamentalists are especially vulnerable to Progressivism. Fundamentalists rarely are able to recover real religious life. They wander through life god-gutted and empty, able only to stop the Fundamentalist habits, but unable to re-conceive religious life in order to live it. Then something like Progressivist Fundamentalism comes along and the sheer familiarity of it is seductive. Fundamentalism kicks back into motion with new omniscient fervor.
New drug, old habit.
I will say it again: the distance between Fundamentalisms is paper-thin. The distance between Fundamentalism (and its always-oppressive political agendas) and authentic religion (and its liberal agenda — yes liberal religion is the purest form!) is vast.