John Calvin Commentary 1 John 4:5

"They are of the world: therefore speak they [as] of the world, and the world heareth them." — 1 John 4:5 (ASV)

They are of the world. It is no small consolation that those who dare to assail God in us have only the world to aid and help them. And by 'the world,' the Apostle means that portion of which Satan is the prince. Another consolation is also added when he says that the world embraces through the false prophets what it acknowledges as its own. We see what a great propensity to vanity and falsehood there is in people. Therefore, false doctrines easily penetrate and spread far and wide. The Apostle intimates that there is no reason why we should be disturbed by this, for it is nothing new or unusual that the world, which is wholly fallacious, should readily listen to what is false.