62 The Apostle of the Gentiles had this to say to the Christian of his day: "Bear not the yoke with unbelievers. For what participation hath justice with injustice? Or what fellowship hath light with darkness? . . . Or what part hath the faithful with the unbeliever?" (40) Hence the duty of modern educators and teachers in the Church of reminding young Catholics of their privileged position and of their obligation to live in the world, but not as the world lives. As Jesus Christ said in His prayer for His apostles: "I pray not that thou shouldst take them out of the world, but that thou shouldst keep them from evil. They are not of the world, as I also am not of the world.'' (41) Church makes this prayer its own.
Source: Ecclesiam Suam (Vatican.va)