There are constant warnings in fundamentalism not to get too close to the world and worldly people. The idea seems to be that sinners will always cause Christians to sin rather than Christians making sinners more holy. For this reason, fundamentalists organize their own schools, sports teams, drama clubs, and social activities lest being in proximity to the unrighteous somehow should soil them. It would seem that sanctification is a very fragile thing indeed that only requires the tiniest of temptations to crumble completely.
This so called “doctrine of separation” has created many illustrations that are familiar to any fundamentalist. Stories of the clean glass and the dirty glass, the canary that learns to sing like the crow, and the drop of poison in the good food are repeated over and over. Evil always triumphs over good. It’s a wonder that anybody ever manages to stay pure.
How exactly we are to be salt and light in the world if we never actually spend any time in the world is unclear. Evidently, Christians are supposed to go out like hunting parties (always two by two, never alone!), club the nearest sinner and drag them back into the haven of the church. After all, that’s what Jesus did. He never spent time with sinners.
If you think that the Amish have the right idea about how to deal with the temptations of the world, then you may very well be a fundamentalist.