For over all is the Father; and through all is the Son, for through Him all things were made by the Father; and in us all is the Spirit, who cries Abba Father (cf. Gal. 4:6), and fashions man into the likeness of God.
Now the Spirit shows forth the Word, and therefore the prophets announced the Son of God; and the Word utters the Spirit, and therefore is Himself the announcer of the prophets, and leads and draws man to the Father.
This then is the order of the rule of our faith, and the foundation of the building, and the stability of our conversation: God, the Father, not made, not material, invisible; one God, the creator of all things: this is the first point of our faith.
The second point is: The Word of God, Son of God, Christ Jesus our Lord, who was manifested to the prophets according to the form of their prophesying and according to the method of the dispensation of the Father:
through whom all things were made; who also at the end of the times, to complete and gather up all things, was made man among men, visible and tangible, in order to abolish death and show forth life and produce a community of union between God and man.
And the third point is: The Holy Spirit, through whom the prophets prophesied, and the fathers learned the things of God, and the righteous were led forth into the way of righteousness; and who in the end of the times was poured out in a new way upon mankind in all the earth, renewing man unto God.
And for this reason the baptism of our regeneration proceeds through these three points: God the Father bestowing on us regeneration through His Son by the Holy Spirit. For as many as carry (in them) the Spirit of God are led to the Word, that is to the Son; and the Son brings them to the Father; and the Father causes them to possess incorruption.
Without the Spirit it is not possible to behold the Word of God, nor without the Son can any draw near to the Father: for the knowledge of the Father is the Son, and the knowledge of the Son of God is through the Holy Spirit; and, according to the good pleasure of the Father, the Son ministers and dispenses the Spirit to whomsoever the Father wills and as He wills.
Irenaeus of Lyons (2nd century AD – c. 202): Demonstration of the Apostolic Preaching, 5-7.