Last night I was sitting in front of our college with my colleague and friend, Brad Nassif, nibbling away on our dinners and we struck up a conversation about Irenaeus’ great book,Demonstration of the Apostolic Preaching. Brad said something I want to explore more carefully and to do this I’d like to begin a series on this little treatise of Irenaeus’.

Brad’s comment: I tell my students that the crucial century was not the 4th, but the 2nd. That is, the ball rolled toward Nicea not because of the events of the 4th Century but because of the ball that was set in motion in the 2d. And that means Irenaeus.
Now a second reason why I want to look at Demonstration: systematic theologies bore me, not so much because of their content but because of their prose and their genre. Detail followed by detail in such a manner that I’m put to sleep. Shouldn’t a description of our faith, I say to myself, be more lively, more story-fied, more narrative, more in tune with the Bible. So this is why we need to look at Irenaeus: his is the first real theology of the earliest churches.
The text is available in various formats, but I love the brief introduction and notes by John Behr, an expert on the fathers. The text comes from somewhere between 150 and 200 AD and Irenaeus tells Marcianus, his addressee, that he is giving a “summary memorandum” of the faith so he can “understand all the members of the body of truth.” In a set of lines that remind of Didache’s opening, he says that one way leads to the kingdom of heaven, “uniting man to God,” and the other to “death, separating man from God.”
Eternity, in other words, is at stake.
Humans are body and soul, the former for physical devotion and the latter for spiritual. The body and the soul work together; they cannot be “dualized.”
His plea, now in paragraph 3, is that “we must keep the rule (kanon) of faith unswervingly, and perform the commandments of God.” Faith is the truth as well as adherence to the truth.