John 17:15

I pray not that thou shouldest take them from the world, but thou shouldest keep them from the evil one.

From ... is from the Greek term meaning "out of," and the obvious reason Jesus did not wish the disciples to be taken out of the world was that such a thing would have made impossible the conversion of the world. That the disciples should be kept "out of" the devil was the important thing. The whole concept underlying asceticism which arose in post-apostolic times was based on a failure to appreciate the meaning of these words. It was Christ's desire that the apostles should remain in the world, in contact with its populations, exposed to its culture, and in direct confrontation with its evil. Only this could enable them to convert the world. In this verse also appears the Saviour's concern for the whole of humanity, the only hope of which was dependent on the apostles' proclamation of the truth.