In alot of ways, American Protestant culture has alot in common with Marxist states in that there's a prevalent cultural idea that there are very few real/legitimate Christians/Marxists/Communists and that we must all be on the lookout for the Enemy's plans to bring us down. Christianity sees "The World" (a big catchphrase in the Black church) as the enemy, and Marxism sees the Capitalists and Counter-revolutionaries the same way.

Maybe that's a cultural relic from the early days of extreme Christian persecution in the Roman world. Or perhaps it come from the early days of the Reformation in Western Europe when it still wasn't entirely clear if Protestantism would survive.