John the Apostle
1 John 4:3KJV·traditional attribution

And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world.

John Calvin Reformed

3. And this is that spirit of Antichrist The Apostle added this, to render more detestable the impostures which lead us away from Christ. We have already said that the doctrine respecting the kingdom of Antichrist was well known; so that the faithful had been warned as to the future scattering of the Church, in order that they might exercise vigilance.

Matthew Henry Presbyterian

The apostle, having said that God's dwelling in and with us may be known by the Spirit that he hath given us, intimates that that Spirit may be discerned and distinguished from other spirits that appear in the world; and so here, I. He calls the disciples, to whom he writes, to caution and scrutiny about the spirits and spiritual professors that had now risen. 1.

Commenting on 1 John 4:1-3

John Gill Reformed Baptist

And every spirit that confesseth not,.... The proper deity and sonship of Christ, his true and real humanity, and his Messiahship; or any of his offices, doctrines, and ordinances; or his satisfaction and righteousness; or that peace, pardon, justification, life, and salvation, are by him; all which are meant by what follows, that Jesus Christ is come in the flesh: this clause is left out...