That's quite interesting history of the creationist folks.
I can't help but note that while the fundamentalist/creationist people have been gathering momentum for decades, the influence of Christian denominations in secular life has been declining.
My theory is that these fundamentalist movements have been "dumbing down" members of Christian churches. It's much easier to lead those who have completely handed over any critical thinking to their leaders. So churches get "stronger", but at the cost of losing members who actually have a skill of evaluating information on their own.
Good analysis, but hardly a theory. ;-)