No soul sleep before the resurrection

For as the Lord “went away in the midst of the shadow of death,” where the souls of the dead were, yet afterwards arose in the body, and after the resurrection was taken up [into heaven], it is manifest that the souls of His disciples also, upon whose account the Lord underwent these things, shall go away into the invisible place allotted to them by God, and there remain until the resurrection, awaiting that event; then receiving their bodies, and rising in their entirety, that is bodily, just as the Lord arose, they shall come thus into the presence of God.

Irenaeus of Lyons
Against Heresies, Book V
Chapter XXXII

 

The number of the beast: 666, not 616

I do not know how it is that some have erred following the ordinary mode of speech, and have vitiated the middle number in the name, deducting the amount of fifty from it, so that instead of six decads they will have it that there is but one. [I am inclined to think that this occurred through the fault of the copyists, as is wont to happen, since numbers also are expressed by letters; so that the Greek letter which expresses the number sixty was easily expanded into the letter Iota of the Greeks.]

But, knowing the sure number declared by Scripture, that is, six hundred sixty and six…

Irenaeus of Lyons
Against Heresies, Book V
Chapter XXX

 

Men bring Hell on themselves. It’s not a punishment.

Now, good things are eternal and without end with God, and therefore the loss of these is also eternal and never-ending. It is in this matter just as occurs in the case of a flood of light: those who have blinded themselves, or have been blinded by others, are for ever deprived of the enjoyment of light. It is not, [however], that the light has inflicted upon them the penalty of blindness, but it is that the blindness itself has brought calamity upon them: and therefore the Lord declared, “He that believeth in Me is not condemned,” that is, is not separated from God, for he is united to God through faith.

Irenaeus of Lyons
Against Heresies, Book V
Chapter XXVII

Man is saved by grace

And justly indeed is he led captive, who had led men unjustly into bondage; while man, who had been led captive in times past, was rescued from the grasp of his possessor, according to the tender mercy of God the Father, who had compassion on His own handiwork, and gave to it salvation, restoring it by means of the Word—that is, by Christ—in order that man might learn by actual proof that he receives incorruptibility not of himself, but by the free gift of God.

Irenaeus of Lyons
Against Heresies, Book V
Chapter XXI

 

Through the “person” of the Spirit we see

These things, therefore, He recapitulated in Himself: by uniting man to the Spirit, and causing the Spirit to dwell in man, He is Himself made the head of the Spirit, and gives the Spirit to be the head of man: for through Him (the Spirit) we see, and hear, and speak.

Irenaeus of Lyons
Against Heresies, Book V
Chapter XX

The Church is the paradise of Eden

…but to flee to the Church, and be brought up in her bosom, and be nourished with the Lord’s Scriptures. For the Church has been planted as a garden (paradisus) in this world; therefore says the Spirit of God, “Thou mayest freely eat from every tree of the garden,” that is, Eat ye from every Scripture of the Lord; but ye shall not eat with an uplifted mind, nor touch any heretical discord.

Irenaeus of Lyons
Against Heresies, Book V
Chapter XX

The catholicity of the Church

But the path of those belonging to the Church circumscribes the whole world, as possessing the sure tradition from the apostles, and gives unto us to see that the faith of all is one and the same, since all receive one and the same God the Father, and believe in the same dispensation regarding the incarnation of the Son of God, and are cognizant of the same gift of the Spirit, and are conversant with the same commandments, and preserve the same form of ecclesiastical constitution, and expect the same advent of the Lord, and await the same salvation of the complete man, that is, of the soul and body.

…For the Church preaches the truth everywhere, and she is the seven-branched candlestick which bears the light of Christ.

Irenaeus of Lyons
Against Heresies, Book V
Chapter XX

To be spiritual is to be embodied, not disembodied

In like manner we do also hear many brethren in the Church, who possess prophetic gifts, and who through the Spirit speak all kinds of languages, and bring to light for the general benefit the hidden things of men, and declare the mysteries of God, whom also the apostle terms “spiritual,” they being spiritual because they partake of the Spirit, and not because their flesh has been stripped off and taken away, and because they have become purely spiritual. For if any one take away the substance of flesh, that is, of the handiwork [of God], and understand that which is purely spiritual, such then would not be a spiritual man but would be the spirit of a man, or the Spirit of God.

…For that flesh which has been moulded is not a perfect man in itself, but the body of a man, and part of a man. Neither is the soul itself, considered apart by itself, the man; but it is the soul of a man, and part of a man.

Irenaeus of Lyons
Against Heresies, Book V
Chapter VI