Peter van Greenaway was a British novelist, and Judas! (published in the U.S. under the less sensational title The Judas Gospel) was one of several thrillers with a slightly misanthropic and pessimistic cast. Although successful during his lifetime—his 1973 novel The Medusa Touch was made into a motion picture starring Richard Burton and Lee Remick—by 2008 (twenty years after his death) he had become obscure enough to be listed among the Indepdendent's "Forgotten Authors." Despite his many novels, little information about him beyond his literary production remains extant (see this bit of sleuthing from an author-blogger in 2010.)

The Judas Gospel is the first of the more noir thrillers to appear (see also Gospel Truths). Like many noir fictions, the sense of hero and villain is skewed and disrupted. None of the characters can be said to be heroic; even the British adventurer on the hunt for a new scroll, who dies early on in the novel, is as much a caricature of the colonialist adventurer as a worthwhile figure. Likewise the sinister Vatican assassin leaving a trail of bodies in his wake is one of the few characters with a clear and unwavering sense of mission and purpose. 

Hero: See above; perhaps the only truly "heroic" figures to emerge in the novel are the Israeli authorities who, it is revealed, have copied and translated the lost gospel and share it disinterestedly with the world at large. It is also possible to read "The Dominican," the brilliant, shape-shifting Vatican assassin sent to stop knowledge from the gospel spread by any means necessary, as a noir hero: the only one who realizes the moral truth at the end of the novel, about the hypocritical foundations of the Church, and remains true to his own mission. 
Villains: Most of the putatively heroic characters, such as the adventuring British archaeologist Lonsdale who has dreamed of finding a new gospel or the innocent bystanders, such as Mallory's friends the Johnsons, reveal themselves to be ultimately self-interested. The most villainous, pusillanimous character may be Mallory, the third-rate semiticist who discover the gospel, smuggles it out of Israel, and attempts to blackmail the Vatican into buying it from him. His naked self-interest mirrors that revealed of the apostle Peter in the lost gospel.
Gospel: An authentic "Gospel of Judas" discovered entirely by chance in the area in which the Dead Sea Scrolls were discovered decades earlier. A first-person account left by Judas, it recounts that Peter actually betrayed Christ and went on to found a duplicitous church in his name

Reviews: Van Greenaway was not an unknown or unliked author and received national reviews in both the U.K. and the U.S. Kirkus Reviews describes the novel as "highly literate," echoing the Times of London's brief notice.  The Birmingham (U.K.) Post (see below) compares Judas! favorably with The Word; the New York Times calls it "absorbing" (see further below). Sites like Goodreads and Amazon have very few reviews, suggesting that, unlike some other Gospel Thrillers from the 1970s, The Judas Gospel has not found a present-day audience.