Beloved, do not believe every spirit, but test the spirits, whether they are of God; because many false prophets have gone out into the world.
By this you know the Spirit of God: Every spirit that confesses that Jesus Christ has come in the flesh is of God,
and every spirit that does not confess that Jesus Christ has come in the flesh is not of God. And this is the spirit of the Antichrist, which you have heard was coming, and is now already in the world.
References for 1 John 4:3
You are of God, little children, and have overcome them, because He who is in you is greater than he who is in the world.
They are of the world. Therefore they speak as of the world, and the world hears them.
We are of God. He who knows God hears us; he who is not of God does not hear us. By this we know the spirit of truth and the spirit of error.