Martin Scorsese has literally been trying for decades to mount an English screen adaptation of Shusaku Endo’s 1966 novel—a Japanese version, directed by Masahiro Shinoda from a script he co-wrote with the novelist, appeared in 1971—and the long-delayed result suggests that over the course of the protracted gestation process the material has perhaps somewhat atrophied in his hands. “Silence” turns out to be a curiously passionless passion project, a film that treats of great themes without attaining greatness itself. One can admire its ambition and craft, but while it raises important questions about religious faith and cultural identity, ultimately it fails to engender the devastating emotional impact it’s clearly aiming for.

The story is set in seventeenth-century Japan, in the aftermath of the Shimabara Rebellion of 1637-38, an uprising in the southwest of the island (the region around Nagasaki), mostly by recently-converted Christian peasants, against the Tokugawa shogunate. Previously sporadic persecution of Christians was now strictly enforced and western missionaries especially targeted. Two young Portuguese Jesuits—Sebastiao Rodrigues (Andrew Garfield) and Francisco Garrpe (Adam Driver)—receive permission from their superior (Ciaran Hinds) to travel to the dangerous region not merely to minister to the remaining Christians but to search for their revered mentor Cristavao Ferreira (Liam Neeson), who is reported to have renounced his faith during the persecution—an act of apostasy they cannot believe.

Smuggled into Japan from the slums of Macao by Kichijiro (Yosuke Kubozuka), a dissolute Japanese man who has himself apostatized and been traumatized by the experience, the priests find some hidden Christians with whom Rodrigues remains while Garrpe continues into the interior. The narrative focus is henceforth on Rodrigues, who witnesses the arrival of government forces led by the chief inquisitor, Inoue Masashige (Issey Ogata) and, taken prisoner, is compelled to watch villagers who refuse to deny their faith by trampling on an image of Christ gruesomely martyred.

The remainder of the film depicts the cat-and-mouse game between Rodrigues and the cunning, chatty inquisitor, who aims to entice the priest to apostatize, an act which would certainly demoralize the local Christians but also represent a cultural triumph of sorts. His methods are not terribly subtle but certainly effective—he makes the priest witness the brutally prolonged torture of his “flock” as well as the strange, elaborately staged combination of martyrdom and execution of Garrpe, and to cap the effort brings Ferreira, who has in fact renounced the faith and even taken a Japanese wife, to persuade his pupil to do likewise.

The issues raised by “Silence” are profound ones. Is one obligated to remain steadfast in adherence to one’s religious belief, even if doing so brings unimaginable pain to others? Or can a person, to save himself or others, go through the motions of apostatizing? This is hardly an issue new to seventeenth-century Japan: after all, Christians faced it during the Roman persecutions of the fourth century, when debate about those who had publicly lapsed gave rise to the Donatist movement. The film presents it not only by portraying Rodrigues’ agonized doubt over what to do—a circumstance exacerbated by the titular silence of God in response to his prayers (which, to the faithful, should recall the words of the crucified Christ addressed to God according to Matthew)—but by presenting the very plausible, very pragmatic arguments of the inquisitor and Ferreira that stand in sharp contrast to the lack of divine instruction. There is also the example of Kichijiro, who reappears periodically as both a tragic figure and a comic one, and who persistently asks for the forgiveness afforded by the sacrament of confession each time he lapses under pressure.

In the end, “Silence,” leaves those questions about apostatizing open, preferring a final act modeled after the latter years of the actual Jesuit, Giuseppe Chiara, on whom Rodrigues is loosely based, but adding a final twist that adds to the ambiguity. It is less enigmatic in its attitude toward cultural exceptionalism, implying that both the Western and the Japanese presumptions of superiority are deeply flawed.

However one might assess the propriety of apostasy under the sort of dire circumstances depicted in the film, what undermines the potency of Scorsese’s treatment of Rodrigues’ embodiment of the issue is a lack of dramatic urgency in the telling. There’s a staid, reverential quality to the entire proceeding, with each sequence—including the portrayals of martyrdom and torture (harrowing but discreet)—presented as virtual tableaux played out with not only appropriate seriousness, but with a degree of solemnity that drains them of much of their power.

The problem is exacerbated by most of the performances. Garfield suffers extravagantly—just as he does in the second half of “Hacksaw Ridge”—but he fails to convey to the full the priest’s psychological confusion and near despair. By contrast Driver and Neeson, hampered by their sketchily drawn characters, are relatively bland. No wonder one is drawn, however reluctantly, to Ogata, whose unnervingly cogent arguments, coupled with a measure of sophistication that allows him even to allow occasionally disparaging comments about his own realm (and combined with the actor’s elfin presence) bring a welcome dose of sheer theatricality to what otherwise comes across as a dirge-like affair. (Of course, secularism has something to do with our reaction as well: the effect isn’t unlike the audience’s tendency to gravitate toward Spencer Tracy over Fredric March while watching “Inherit the Wind.”) The issue here might be as simple as the difficulty of film getting inside a person’s head in the way that a novel can, but it’s a fundamental flaw nonetheless.

Moreover, there is an ancillary failing in the unwillingness of the script to deal with the Japanese Christians in any meaningful sense. The locals—apart from the inquisitor and his minions, and Kichijiro of course—come across as ciphers who merely suffer or apostatize as the script demands. The nature and depth of their belief are matters that are occasionally discussed by the main characters, but that is all secondary information, of course; they never really speak for themselves.

And yet despite these problems it is not easy to dismiss “Silence.” As edited by Thelma Schoonmaker, it is slow, often to the point of turgidity, and never manages to shed the relatively arid atmosphere of a thesis. But it is unquestionably the work of a master—working with cinematographer Rodrigo Prieto on Taiwanese locations, with Dante Ferreti contributing an impressive production design, Scorsese achieves many striking images.

Even more importantly, the film grapples with subjects that obviously matter to the director: one feels his dedication to addressing the tension between the demands of religious belief and one’s obligations to other human beings, between doctrinaire practice and personal compassion, between devotion to God and love of one’s fellow man. If one wished to be crass in boiling down the issues it raises, one might cite the popular query, “What would Jesus do?” though that would be an unjust oversimplification of the director’s purpose. Scorsese’s epic-length film of Endo’s novel is a challenging, dramatically frustrating but cinematically gifted examination of a central question of religious faith, presented in the context of particular historical and cultural circumstances but with universal implication—a flawed but committed work by one of the medium’s greatest directors.