Some evangelical Christians hold to an interpretation of Bible prophecy known as the post-tribulation rapture, in which the world will have to go through a seven-year period of war and global dictatorship known as the "Great Tribulation". Jim McKeever helped popularize survival preparations among this branch of evangelical Christians with his 1978 book Christians Will Go Through the Tribulation, and How To Prepare For It.
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!