J.G. Sandom grew up between Europe and the United States, and has been writing novels since college. He seems to have made his fortune in digital advertising in the 1980s and 1990s and began his career as a writer with Gospel Truths in 1992. The biography Sandom has posted to his website describes two earlier novels being "released" in 1975 and 1981 (before and after his graduation from Amherst), but these earlier novels (described elsewhere as "practice novels") do not seem to be commercially available. Gospel Truths was his public novelist debut.
In an interview in 2007, Sandom provided some background on Gospel Truths, including its relationship with his own upbringing, actual events surrounding Vatican banking scandals in the 1980s, and his personal relationship with one of the archbishops involved in the scandal, his cousin. As this interview demonstrates, Gospel Truths has a lot of not quite coherently connected threads running through it: gnosticism, masons, cathedrals, banking, the Vatican, the French countryside, and so on. The Pinterest page Sandom has compiled for the book gives a sense of its meandering scope.
The novel has a sharply noir tone, focused as it is on the bedraggled and haunted hero, the London police officer Nigel Lyman. The secondary hero, Joseph Koster, resonates more clearly with Sandom's own biography and appears in less noir and more computer-oriented fantastical sequel to this novel, The God Machine (see below).
Heroes: Nigel Lyman, an alcoholic and disgraced London cop given a second chance to make things right; Joseph Koster, a U.S. architect raised in Europe investigating mathematical mysteries in medieval cathedrals; both Lyman and Koster have lost sons before the novel begins
Villains: Members of a secretive lodge called Informazione Quattro (IQ, or I-Four), particularly the venal smuggler Marco Scarcella and Vatican banker Archbishop Grabowski, working with various European Masonic conspirators
Gospel: A medieval copy of the Book of Thomas the Contender leads to an early version of The Gospel of Thomas which leads ultimately to Q, in which Jesus preaches a gnostic variety of liberation theology (explicitly invoked in the book)
SEQUEL: Koster appears again the main hero (now with Asperger's Syndrome) in The God Machine, a 2009 sequel to Gospel Truths. While the center of The God Machine seems to be another lost gospel—here, an authentic earlier version of the Gospel of Judas found in the Tchacos Codex—the complex mathematics of the story actually lead to a mysterious chip that powers "the God Machine," a powerful tool also sought, in flashbacks, by Benjamin Franklin (without success). The "machine" turns out to be the human brain, capable of clairvoyance and insight when tuned to the correct frequency, discovered and hidden by Judas. The gospel—and even the "machine"—of the title turn out to be MacGuffins. Various elements relevant to the Gospel Thrillers project are recycled from Gospel Truths (including multiple para-religious fanatical agents, notably a killer nun); the other elements belong to science fiction and philosophy of mind. I have decided to exclude The God Machine from my study.
J.G. Sandom has collected a smattering of highly positive published and reader reviews on his website; see also this standalone review posted there. The novel did not receive much notice in the press. Kirkus Reviews described the debut novel as "weightless." The publication of The Da Vinci Code and Sandom's own efforts at promotion have kept Gospel Truths in print. Bantam still seems to have the book in press, but Sandom has also published an updated version in 2013 through his own vanity press, Cornucopia Press (the announcement here includes possible casting ideas.) Reviewers at Goodreads have given the book generally positive ratings.