John Calvin Commentary John 17:14

"I have given them thy word; and the world hated them, because they are not of the world, even as I am not of the world." — John 17:14 (ASV)

I have given them Your word. He employs a different argument in pleading with the Father on behalf of the disciples. This is because they need His assistance on account of the hatred of the world. He also declares the cause of that hatred to be that they have embraced the word of God, which the world cannot receive; as if He had said, “It belongs to You to protect those who, on account of Your word, are hated by the world.”

We must now remember what we have recently heard: that the end of this prayer is that Christ’s joy may be fulfilled in us. Therefore, whenever the rage of the world is kindled against us to such an extent that we think we are very near destruction, let us learn to suddenly ward it off with this shield: that God will never forsake those who labor in defense of the Gospel.

Because they are not of the world. He says that His disciples are not of the world, because all those whom He regenerates by His Spirit are separated from the world. God will not allow His sheep to wander among wolves without showing Himself to be their shepherd.