Let's look at his footnote #1. This is from the text of his article:
Scholars and popular historians routinely utilize secondary sources or take quotations from these sources, 1 but when David returned to this subject for his 1996 book Original Intent, he decided to only rely on quotations that could be found in original primary source material.And here is the content of the footnote:
1. See, for instance, Mark A. Noll, Nathan O. Hatch, and George M. Marsden, The Search for Christian America (Westchester: Crossway Books, 1983), passim and especially p. 73 (citing various secondary source to support the profoundly erroneous assertion that “The God of the founding fathers was a benevolent deity, not far removed from the God of eighteenth-century Deists or nineteenth century Unitarians.”); John Fea, Was America Founded as a Christian Nation: A Historical Introduction (Louisville: Westminster John Knox Press, 2011),118-19, 258 (quoting John Calvin from Gregg Frazer’s 2004 doctoral dissertation rather than the readily available Institutes of the Christian Religion); and, worst of all, Isaac Kramnick and R. Laurence Moore, The Godless Constitution: The Case Against Religious Correctness (New York: W.W. Norton, 1996) (within which the authors do not feel compelled to cite any sources whatsoever!).Google Noll, Hatch and Marsden for their bona fides. Barton certainly has nerve. Barton intimates that if a scholar cites another scholar as opposed to a primary source, the original sources are not being accurately cited. Now, this can happen. Indeed, this scholarly malpractice is what caused the problem with his "unconfirmed quotations."
For example, George Washington says something in his Farewell Address where he uses the terms "religion" and "morality" providing "indispensable supports" to civic society. A secondary or even later source comments on it with spin: "Washington was saying it is impossible to rightly govern the world without God and the Bible." Then a later source says "George Washington said 'it's impossible to govern ...'" (For more on the story, see this.)
Again, it's scholarly malpractice and it is something in which NONE of the above mentioned scholars engage. They are not just "citing each other" instead of citing the primary sources, which is what Barton intimates. Rather, they are accurately quoting the primary sources, giving critical commentary, providing the critical commentary of other professionals and the footnotes often go, instead of to a primary source, to a secondary source that is respected and peer reviewed.
I prefer the more straightforward footnote directly to the primary source. But the accuracy and context of the quotations can be verified. And indeed, I just verified the footnotes and sources on pages 72-74 of The Search For Christian America. They are all accurate as is their assertion “The God of the founding fathers was a benevolent deity, not far removed from the God of eighteenth-century Deists or nineteenth century Unitarians.”
One caveat, if "Deism" is understood as the cold, distance watchmaker, it would be misleading. However the God of the 18th Century American and English "Deists" was chiefly "Christian-Deism." Indeed, it's hard to imagine describing a cold, non-intervening watchmaker as "benevolent" as the authors do (and the Founding Fathers did). Further, the God of the nineteenth century Unitarians (at least for most of that century) was understood as a "Christian" deity with a consequent denial of the Trinity and affirmation of unorthodox understandings of biblical texts and doctrines.
So Barton, not the three "PhDs," (what Barton doesn't have and seemingly views those who do have them with hostility) is the one who is "profoundly erroneous" in his assertions.
Likewise, Dr. Fea accurately quotes from John Calvin and lists the source Dr. Frazer's PhD dissertation which accurately quotes from Calvin's Institutes. He also sources Calvin's Institutes on footnote 22 of Chapter 7 of his book.
Drs. Kramnick and Moore likewise accurately quote the original sources which they cite, but simply dispense with the normal method of scholarly footnoting (a mistake in my opinion). Here and elsewhere Barton gives the misimpression that they have "no sources" when in reality they simply have no footnotes or endnotes. Their book is, again to stress the point, replete with accurate quotations from original sources. (I don't think one could establish a life long successful career at Cornell as each of them did, without being able to accurately cite original material.)