Quotes

Christ spoke through the prophets and they named Him God

But by the law and the prophets did the Word preach both Himself and the Father alike [to all]; and all the people heard Him alike, but all did not alike believe. And through the Word Himself who had been made visible and palpable, was the Father shown forth, although all did not equally believe in Him; but all saw the Father in the Son: for the Father is the invisible of the Son, but the Son the visible of the Father. And for this reason all spake with Christ when He was present [upon earth], and they named Him God.

Irenaeus of Lyons
Against Heresies, Book IV
Chapter VI

The Father and the Word are Creator

For by means of the creation itself, the Word reveals God the Creator; and by means of the world [does He declare] the Lord the Maker of the world; and by means of the formation [of man] the Artificer who formed him; and by the Son that Father who begat the Son: and these things do indeed address all men in the same manner, but all do not in the same way believe them.

Irenaeus of Lyons
Against Heresies, Book IV
Chapter VI

The Father made His Word visible

And for this purpose did the Father reveal the Son, that through His instrumentality He might be manifested to all, and might receive those righteous ones who believe in Him into incorruption and everlasting enjoyment (now, to believe in Him is to do His will); but He shall righteously shut out into the darkness which they have chosen for themselves, those who do not believe, and who do consequently avoid His light. The Father therefore has revealed Himself to all, by making His Word visible to all; and, conversely, the Word has declared to all the Father and the Son, since He has become visible to all. And therefore the righteous judgment of God [shall fall] upon all who, like others, have seen, but have not, like others, believed.

Irenaeus of Lyons
Against Heresies, Book IV
Chapter VI

Irenaeus quotes Justin Martyr against Marcion

In his book against Marcion, Justin does well say: “I would not have believed the Lord Himself, if He had announced any other than He who is our framer, maker, and nourisher. But because the only-begotten Son came to us from the one God, who both made this world and formed us, and contains and administers all things, summing up His own handiwork in Himself, my faith towards Him is stedfast, and my love to the Father immoveable, God bestowing both upon us.”

Irenaeus of Lyons
Against Heresies, Book IV
Chapter VI

Faith towards God justifies a man

The Lord, therefore, was not unknown to Abraham, whose day he desired to see; nor, again, was the Lord’s Father, for he had learned from the Word of the Lord, and believed Him; wherefore it was accounted to him by the Lord for righteousness. For faith towards God justifies a man;

Irenaeus of Lyons
Against Heresies, Book IV
Chapter V

Souls continue to exist after death

For if He be not the God of the dead, but of the living, yet was called the God of the fathers who were sleeping, they do indubitably live to God, and have not passed out of existence, since they are children of the resurrection.

Irenaeus of Lyons
Against Heresies, Book IV
Chapter V

Ignoring heresy is not an option

Wherefore it shall not weary us, to endeavor with all our might to stretch out the hand unto them. Over and above what has been already stated, I have deferred to the following book, to adduce the words of the Lord; if, by convincing some among them, through means of the very instruction of Christ, I may succeed in persuading them to abandon such error, and to cease from blaspheming their Creator, who is both God alone, and the Father of our Lord Jesus Christ. Amen.

Irenaeus of Lyons
Against Heresies, Book III
Chapter XXV

The Holy Spirit through the Church is the ladder of ascent to God

But [it has, on the other hand, been shown], that the preaching of the Church is everywhere consistent, and continues in an even course, and receives testimony from the prophets, the apostles, and all the disciples—as I have proved— through [those in] the beginning, the middle, and the end, and through the entire dispensation of God, and that well-grounded system which tends to man’s salvation, namely, our faith; which, having been received from the Church, we do preserve, and which always, by the Spirit of God, renewing its youth, as if it were some precious deposit in an excellent vessel, causes the vessel itself containing it to renew its youth also. For this gift of God has been entrusted to the Church, as breath was to the first created man, for this purpose, that all the members receiving it may be vivified; and the [means of] communion with Christ has been distributed throughout it, that is, the Holy Spirit, the earnest of incorruption, the means of confirming our faith, and the ladder of ascent to God.

…For where the Church is, there is the Spirit of God; and where the Spirit of God is, there is the Church, and every kind of grace; but the Spirit is truth.

Irenaeus of Lyons
Against Heresies, Book III
Chapter XXIV