Catena Fidei

1 John 4:2 (WEB)
By this you know the Spirit of God: every spirit who confesses that Jesus Christ has come in the flesh is of God,

Catechism · 3

§423Chapter Two · I Believe in Jesus Christ, the Only Son of GodRead at vatican.va
“He 'came from God', 'descended from heaven', and 'came in the flesh'.” — Catechism footnote: 1 Jn 4:2.

§463Paragraph 1 · The Son of God Became ManRead at vatican.va
“Belief in the true Incarnation of the Son of God is the distinctive sign of Christian faith: "By this you know the Spirit of God: every spirit which confesses that Jesus Christ has come in the flesh is of God."” — Catechism footnote: I Jn 4:2.
§465Paragraph 1 · The Son of God Became ManRead at vatican.va
“From apostolic times the Christian faith has insisted on the true incarnation of God's Son "come in the flesh".” — Catechism footnote: Cf. I Jn 4:2-3; 2 Jn 7.

Irenaeus of Lyons, Against Heresies III.16Book III
“Hereby know ye the Spirit of God: Every spirit that confesseth that Jesus Christ is come in the flesh is of God; and every spirit which separates Jesus Christ is not of God, but is of antichrist.”” — editor's note: 1 John iv. 1, 2. This is a material difference from the received text of the passage: “Every spirit that confesseth not that Jesus Christ is come in the…
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Tertullian, Against Praxeas Chapter 28
“John, moreover, brands that man as “a liar” who “denieth that Jesus is the Christ;” whilst on the other hand he declares that “every one is born of God who believeth that Jesus is the Christ.”” — editor's note: See 1 John ii. 22, iv. 2, 3, and v. 1.
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Tertullian, The Five Books Against Marcion V.15Book V
“…John, who says that “already many false prophets are gone out into the world,” the fore-runners of Antichrist, who deny that Christ is come in the flesh, and do not acknowledge Jesus (to be the Christ), meaning in God the Creator.” — editor's note: 1 John iv. 1–3.
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Eusebius of Caesarea, Church History VI.12Book VI
“For having obtained this Gospel from others who had studied it diligently, namely, from the successors of those who first used it, whom we call Docetæ (for most of their opinions are connected with the teaching of that school) we have been able to read it through, and we find many things in accordance with…” — editor's note: By Docetism we understand the doctrine that Christ had no true body, but only an apparent one. The word is derived from δοκέω, “to seem or appear.” The belief…
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Theodoret of Cyrus, Dialogues (Eranistes) §2
“…come in the flesh is of God, and every spirit that confesses not that Jesus Christ is come in the flesh is not of God, and this is that spirit of Anti-Christ.”” — editor's note: 1 John iv. 2, 3
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Ambrose of Milan, Exposition of the Christian Faith V.3Book V
“Which also this very Evangelist has taught us elsewhere, saying: “Every spirit that confesseth that Jesus Christ is come in the flesh, is of God.”” — editor's note: 1 John iv. 2.
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John Chrysostom, Homilies on John Homily 10
“For since there are some who say that all the circumstances of the Dispensation were an appearance, a piece of acting, an allegory, at once to remove beforehand their blasphemy, he has put “was made”; desiring to show thereby not a change of substance, (away with the thought,) but the assumption of very flesh.” — editor's note: The Docetæ, who maintained that our Lord appeared only to act and suffer in the Flesh, and that His Body was a phantom. Perhaps they are the heretics specially…
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Augustine of Hippo, Homilies on the First Epistle of John Homily 6
“Our ears, so to say, are on the alert for discerning of the spirits; and we have been told something, such that thereby we discern not a whit the more.” — editor's note: 1 John iv. 2, 3.
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Augustine of Hippo, Homilies on the First Epistle of John Homily 10
““In this we know that we love the sons of God.”” — editor's note: 1 John iv. 2.
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Leo the Great, Letters Letter 158
“…“every spirit which confesses Jesus Christ to have come in the flesh is of God, and every spirit which dissolves Jesus is not of God, but this is antichrist.”” — editor's note: 1 John iv. 2, 3. For the reading solvit (dissolves), cf. Lett. XXVIII. (Tome), chap. 5 and note.
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Leo the Great, Sermons Sermon 34
“…“every spirit which confesses Christ Jesus to have come in the flesh is of God: and every spirit which destroys Jesus is not of God, and this is Antichrist.”” — editor's note: 1 John iv. 2, 3: see Letter XXVIII. (Tome) 5, n. 7, on the various reading.
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Cyprian of Carthage, Three Books of Testimonies Against the Jews II.9Book II
“But whosoever denies that He is come in the flesh is not of God, but is of the spirit of Antichrist.”” — editor's note: 1 John iv. 2, 3.
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