OK. Great. You've stockpiled for the end of the world, you quack. The chances of the world ending are smaller than ... holy crap, what the hell is a supervolcano? See why we're all doomed in 5 Ways The World Could End That You'd Never See Coming. And if that's not enough to get you to build your own bunker, check out 6 Tiny Mistakes That Almost Ended The World. Really, the planet almost ended due to a blown fuse? Come on humanity, let's get it together.
These individuals study End Times prophecy and believe that one of various scenarios might occur in their lifetime. While some Christians (and even people of other religions) believe that the Rapture will follow a period of Tribulation, others believe that the Rapture is imminent and will precede the Tribulation ("Pre-Trib Rapture"). There is a wide range of beliefs and attitudes in this group. They run the gamut from pacifist to armed camp, and from having no food stockpiles (leaving their sustenance up to God's providence) to storing decades' worth of food.
To me, the best option is to store emergency food. How much? If you have none, store enough for a few days. If you have enough for a few days, get enough for a week. How much you store depends on what time frame you think you're at risk for having to be completely independent. The early settlers of the southwest liked to store enough food for a whole year and still do to this day!