“But if there be anything touching times or places, which they have related differently,
this nothing injures the truth of what they have said. And these things too, so far as God shall enable us, we will endeavor, as we proceed, to point out; requiring you, together with what we have mentioned, to observe, that in the chief heads, those which constitute our life and furnish out our doctrine, nowhere is any of them found to have disagreed, no not ever so little.
You wrote that the truth that John refers to here in his first sentence refers
only to the truth of the chief heads. And it is my position that it refers to the truth about everything they say. When he says that he is going to require us, “together with what we have mentioned, to observe, that in the chief heads…” he gives indication that he has not yet broached the subject of the chief heads in the way that you suppose. Had he done this, we would rather expect him to have finished out his first sentence by saying more simply, “this nothing injures the truth of what they have said
about the chief heads.” But I do not think he intended to limit himself in this way because defining “truth” as something separable from “facts” doesn’t seem to be the mindset of our author.
We gain an understanding of what he is saying here by examining the large number of examples which serve to demonstrate what he is talking about. They are our best informants because he said that he is going to endeavor by the power of God to point out how the difference in narration touching times or places nothing injures the truth of what they have said. Since John says he is going to do this for us as he goes along, we should ask the question, When he harmonizes the differences concerning the little matters, what does he conclude each time? In my own words, this is what he says: “See how the different material I’ve harmonized doesn’t injure the truth of what they were trying to communicate by that different material!” The truth about the times and places is itself maintained by the different narrations! This truth, as you have pointed out, translates into serving to substantiate the truth of the Gospel, and so what you are saying is implicated by Chrysostom’s assertion; but if the words pertaining to the little things do not first contain the truth of what they themselves represent, then their inherent falseness will obliterate themselves and certainly injure the truth of the chief heads. The two can’t be separated. The truth about “the times and places” in Scripture is valuable to us because it goes beyond bare facts and leads us to the truth about God, and our confidence in our having the truth about God is made sure by this truthfulness in the little matters.
The Christian faith has its specificity, primarily in that it refers to historical events, or better to a coherent history, which actually took place as history. In this sense, the question about the fact, the reality of the event, is essential to it, and must make room for the historical method. But these historical events have meaning for the faith only because it is certain that in them God Himself acted in a specific way and the events contain something which surpasses simple historical facticity, something which comes from elsewhere and gives them meaning for all times and for all people. This surpassing element must not be separated from the facts, it is not a meaning which is subsequently added to them from without, but rather it is present in the event itself, and yet it transcends the purely factual aspect. (Address of Cardinal Joseph Ratzinger,
Current Doctrinal Relevance of the Catechism of the Catholic Church)
Let’s think about a few of the examples:
“But Mark says, ‘In the days of Abiathar the High Priest’ (Mark 2:26):
not stating what was contrary to the history, but implying that he had two names” (
Homily 39 on Matthew).
The implication that he had two names is only there if you presuppose an inerrant text because we have no corroborating evidence that this is true. John’s conclusion in this case is that Mark had not stated what was contrary to the history. In maintaining this congruity between the statement of Mark and the historical fact, there is no direct and immediate impact upon any doctrine of the faith. But had the Gospel writers attempted to make a statement about history and gotten it wrong, then this would be a contradiction and would injure the truth of what they had said, both about Abiathar and, by implication, about everything else too, if by nothing else than by casting the clouds of suspicion and doubt.
This, by the way, is the text that drove Dr. Bart Ehrman into apostasy when he had the unfortunate experience of a professor suggesting, to the contrary of Ehrman’s best efforts, that Mark had simply made a mistake. If Chrysostom had been his instructor, think of the happy results that would have come about!
Something else worth mentioning: how many people in John’s congregation were aware of this apparent historical error? I would say, Not that many, and likely even less than today.

This is telling because a person who is confident in a completely inerrant text is more likely to be the one who brings in unknown examples in order to resolve them.
“The place likewise, and the time, he puts down, to bring to our remembrance ancient prophecies” (
Homily 6 on Matthew).
Here the time and the place are directly connected to Old Testament prophesies. I share this example to illustrate the fact that the little matters are completely interwoven into the history of salvation recorded in the Bible.
“Then, lest you should be confounded at what is going on, and at their strange frenzy, He introduces the prophet also, foretelling all this. For
so great was the accuracy of the prophets, that they omit not even these things, but foretell His very journeyings, and
changes of place, and the intent with which He acted therein; that you might learn, how
they spoke all by the Spirit. For if the secrets of men cannot by any art be known, much more were it impossible to learn Christ’s purpose, except the Spirit revealed it.” (
Homily 40 on Matthew).
The accuracy of the prophets extends even to indicating the places of Jesus’ travels. If the Gospel writers had at any point contradicted each other on these details, then this accuracy would be a strange thing for John to bring attention to.