1:7 - For many deceivers are entered into the world, who confess not that Jesus Christ has come in the flesh. This is a deceiver and an antichrist.
Epistle of Ignatius to the Antiochians
And he that rejects the incarnation, and is ashamed of the cross for which I am in bonds, this man is antichrist.[24]Irenaeus Against Heresies Book III
These are they against whom the Lord has cautioned us beforehand; and His disciple, in his Epistle already mentioned, commands us to avoid them, when he says: "For many deceivers are entered into the world, who confess not that Jesus Christ is come in the flesh. This is a deceiver and an antichrist. Take heed to them, that ye lose not what ye have wrought."[296]Tertullian On Fasting
And how is it that he enjoins duties which belong to our God, and enjoins them to be offered to none other than our God? Either contend that the devil works with our God, or else let the Paraclete be held to be Satan. But you affirm it is "a human Antichrist: "for by this name heretics are called in John.[90]
1:10 - If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed:
Irenaeus Against Heresies Book I
And John, the disciple of the Lord, has intensified their condemnation, when he desires us not even to address to them the salutation of "good-speed; "for, says he, "He that bids them be of good-speed is a partaker with their evil deeds; "[218]Seventh Council of Carthage Under Cyprian
said: John the apostle laid it down in his epistle, saying: "If any one come unto you, and have not the doctrine of Christ, receive him not into your house, and say not to him, Hail. For he that saith to him, Hail, partakes with his evil deeds."[133]