Jesus prayed to His Father, "I do not ask you to take them (His disciples) out of the world, but to keep them from the evil one." The "world" He's referring to are all the people who don't know God, along with all their attitudes that are hostile and ungodly. Our first response is to run away and isolate ourselves. That's why monks went to monasteries in the wilderness, where no one else would go. They were trying to escape from "the world" so they wouldn't be tempted by it. But how could they be "the light of the world" (Matt. 5:14) if they were not in it?

Jesus wants us to go into the world, but He doesn't want the world to get into us. A submarine can't fulfill its purpose if it is out of the water. It must be submerged into the ocean before it can be effective. Even though the sub is surrounded by water, the water can't get inside because it is insulated. The submarine was prepared ahead of time, before it went into the sea, to have all possible areas sealed where leaks could occur.