John 17:14

He tells his Father the reason why the world hated them, because they were not of the world. By generation, indeed, they were of the world; but by regeneration, they were not of the world. Thus they became like to himself, being born again of that Holy Spirit, by whose all powerful operation, he took upon himself the form of a servant. But although they were not of the world, still was it necessary that they should remain in the world; therefore he continues, I ask not that thou wouldst take them out of the world. (St. Augustine, tract. 107. in Joan.)