Distinctives of Irenaeus

The theology of Irenaeus has two distinctive characteristics:

first, the whole of his theology is marked by his contrast between God and the Devil, and the ceaselessly raging conflict between the two powers, a conflict which is fought out in the midst of our humanity; and

second, this humanity, independently of the conflict we have mentioned, is continually in process of change, developing and altering its form, but never remaining in the same fixed pattern.

(paragraph breaks mine, p.104, Gustaf Wingren, Man and the Incarnation: A study in the Biblical Theology of Irenaeus)

Order, foundation and support

Irenaeus in his Demonstration of the Apostolic Preaching:

This then is

• the order of our faith,
• the foundation of our building
• and the support of our conduct:

  God the Father,

• uncreated, uncontainable, invisible;
• one God, the creator of all things:

this is the first point of our faith.

The second point is this:
  the Word of God, Son of God, Christ Jesus our Lord,

• who appeared to the prophets, each characteristically and according to the Father's way of disposing;
• through Christ all things were made,
• and he 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 effect communion between god and man.

And the third point is:
  the Holy Spirit

• through who the prophets prophesied, the patriarchs learned the things of God, and the righteous were led into the way of righteousness;
• and who in the end of times was poured out in a new way upon the human race, renewing man in all the earth unto God.

(my formatting, cited in Geoffrey Wainwright, "Trinity" in, ed Vanhoozer, Dictionary for Theological Interpretation of the Bible)

Great stuff. That dictionary is a funny thing, but it's full of gems.