This is HUGE... and I'm surprised this thread has been ignored for so long. Whether Christian or not, Catholic, liberal Protestant, or Evangelical, you have to admit the influence of John Darby and dispensationalism on the political and religious worlds has been sensational. In the early 20th century, it contributed passively by driving fundamentalist Christians OUT of politics. Up until the mid-1920's Protestants were very active in American politics, working to abolish slavery and bring in Prohibition. They were still running on the gas of postmillenial postivism and/or the social gospel. In the fallout of the fundamentalist-modernist controversy, conservatives left the mainline denominations and retreated to the ghetto of independent seperatism. Dispensationalism had been gaining in popularity due to the Scofield Bible. First it gained popularity in the Episcopal church, then spread to Presbyterianism, and finally it made a permanent home in the Baptist Churches. The negativity of dispensational eschatology (things are just going to keep getting worse until Jesus returns) and the teaching of the imminence of Christ's return gave conservative Christians (who in the past would try to reform society) an excuse to sit back and watch the world go to hell. In the late 20th century, dispensationalism began to work actively by encouraging Christians to engage in political behaviors that might speed up the end times. Falwell, Robertson, and even Reagan began to support Israel with a religious zeal. Environmental issues didn't matter, because this world would be transformed soon anyway. Instead of working constructively to find common ground with Catholics, secular agnostics, labor unions, etc. (as Protestants might have done 100 years previous), Evangelicals got trapped in an "us vs. them" culture war.
It's interesting, John Darby, the father of dispensationalism, gave up a career as a lawyer because he felt the practice of law to be inconsistant with his beliefs. If he had somehow reconciled his beliefs with the legal profession, what a difference that would have made!
I would love to see someone start a timeline of a world sans dispensationalism.