4:1 - Beloved, believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world.

Irenaeus Against Heresies Book 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."[297]
Tertullian Against Marcion Book V
by the Apostle 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,[740]
Dubious Hippolytus Fragments
Believe not every spirit, because many false prophets are gone out into the world."[37]

4:2 - Hereby know all of you the Spirit of God: Every spirit that confesses that Jesus Christ has come in the flesh is of God:

Tertullian Against Praxeas
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."[398]
Cyprian Treatise XII Three Books of Testimonies Against the Jews
But whosoever denies that He is come in the flesh is not of God, but is of the spirit of Antichrist."[184]

4:3 - And every spirit that confesses not that Jesus Christ has come in the flesh is not of God: and this is that spirit of antichrist, whereof all of you have heard that it should come; and even now already is it in the world.

Epistle of Polycarp to the Philippians
"For whosoever does not confess that Jesus Christ has come in the flesh, is antichrist; "[41]
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]
Tertullian The Prescription Against Heretics
But in his epistle he especially designates those as "Antichrists" who "denied that Christ was come in the flesh,"[361]
Tertullian Against Marcion Book V
and do not acknowledge[741]
Tertullian On the Flesh of Christ
the virgin friend of Apelles. Surely he is antichrist who denies that Christ has come in the flesh.[339]
Tertullian On the Resurrection of the Flesh
no one has as yet escaped from Antichrist;[144]
Cyprian Epistle LXXII
how can either darkness illuminate, or unrighteousness justify? And when they say that "they are not of God, but are of the spirit of Antichrist,"[20]

4:4 - All of you are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world.

Cyprian Epistle VIII
re already crowned, while some are even now within reach of the crown of victory; but all whom the danger has shut up in a glorious company are animated to carry on the struggle with an equal and common warmth of virtue, as it behoves the soldiers of Christ in the divine camp: that no allurements may deceive the incorruptible stedfastness of your faith, no threats terrify you, no sufferings or tortures overcome you, because "greater is He that is in us, than he that is in the world; "[2]
Cyprian Treatise XI Exhortation to Martyrdom Addressed to Fortunatus
John, in his epistle, proves this, saying: "Greater is He who is in you than he that is in the world."[70]
Cyprian Treatise XII Three Books of Testimonies Against the Jews
Of this thing also in John: "Greater is He who is in you than he who is in this world."[430]

4:6 - We are of God: he that knows God hears us; he that is not of God hears not us. Hereby know we the spirit of truth, and the spirit of error.

Shepherd of Hermas Commandment Third
How then can I live, since I have acted thus? "And he said to me, "Your feelings are indeed right and sound, for you ought as a servant of God to have walked in truth, and not to have joined an evil conscience with the spirit of truth, nor to have caused sadness to the holy and true Spirit."[5]

4:8 - He that loves not knows not God; for God is love.

Clement of Alexandria Stromata Book IV
"God," then, being good, "is love," it is said.[175]
Lactantius Divine Institutes Book I
But perchance some one may ask of us the same question which Hortensius asks in Cicero: If God is one only,[22]

4:9 - In this was manifested the love of God toward us, because that God sent his only begotten Son into the world, that we might live through him.

Epistle of Polycarp to the Philippians
but endured all things for us, that we might live in Him.[50]

4:12 - No man has seen God at any time. If we love one another, God dwells in us, and his love is perfected in us.

Tertullian Against Praxeas
"And we have seen His glory, the glory as of the only begotten of the Father; "[179]
A Treatise of Novatian Concerning the Trinity
If God cannot be seen, how was God seen? Or if He was seen, how is it that He cannot be seen? For John also says, "No man hath seen God at any time; "[135]

4:15 - Whosoever shall confess that Jesus is the Son of God, God dwells in him, and he in God.

Tertullian Against Praxeas
But "whosoever shall confess that (Jesus) Christ is the Son of God" (not the Father), "God dwelleth in him, and he in God. "[436]
Epitome of the Divine Institutes by Lactantius
Nor let the Jews, or philosophers, flatter themselves respecting the Supreme God. He who has not acknowledged the Son has been unable to acknowledge the Father.[116]

4:16 - And we have known and believed the love that God has to us. God is love; and he that dwells in love dwells in God, and God in him.

Clement of Alexandria Stromata Book IV
And if "God be love," piety also is love: "there is no fear in love; but perfect love casteth out fear."[144]
Clement of Alexandria Stromata Book V
It is not, then, without reason that we commanded boys to kiss their relations, holding them by the ears; indicating this, that the feeling of love is engendered by hearing. And "God," who is known to those who love, "is love,"[30]
Fragments of Clement from the Latin Translation of Cassiodorus
But John himself also in this same Epistle says, "God is love: "[76]
Cyprian Treatise I On the Unity of the Church
The word of the blessed Apostle John is: "God," saith he, "is love; and he that dwelleth in love dwelleth in God, and God dwelleth in him."[43]
Cyprian Treatise XII Three Books of Testimonies Against the Jews
Also in the Epistle of John: "God is love l and he that dwelleth in love dwelleth in God, and God in him."[385]

4:18 - There is no fear in love; but perfect love casts out fear: because fear has torment. He that fears is not made perfect in love.

Shepherd of Hermas Commandment Seventh
For, fearing the Lord, you will not do these deeds, but will refrain from them. For fears are of two kinds:[2]
Clement of Alexandria Who is the Rich Man that Shall Be Saved?
"Perfect love casteth out fear."[70]
Tertullian Scorpiace
affirming that there is no fear in love: "For perfect love casteth out fear, since fear has punishment; and he who fears is not perfect in love."[82]
Tertullian De Fuga in Persecutione
But the man who does not fear to suffer, he will be perfect in love-in the love, it is meant, of God; "for perfect love casteth out fear."[59]
Fragments of the Epistle of Phileas to the People of Thmuis
.[4]

4:20 - If a man say, I love God, and hates his brother, he is a liar: for he that loves not his brother whom he has seen, how can he love God whom he has not seen?

Cyprian Treatise XII Three Books of Testimonies Against the Jews
Also in the same place: "If any one shall say that he loves God, and hates his brother, he is a liar: for he who loveth not his brother whom he seeth, how can he love God whom he seeth not? "[382]