The movie was based on a novel by Brian Moore:
Catholics is a novel by Brian Moore. It was first published in 1972, and was republished with an introduction by Robert Ellsberg and a series of study questions by Loyola Press in 2006.
Most of the action of the novel takes place on an island monastery off the southwest coast of Ireland. It is set in the future, near the end of the twentieth century after the Fourth Vatican Council. The story tells of a young priest sent by the authorities in Rome to fully implement Church reforms in an Irish monastery that still celebrates the Catholic liturgy according to older rites. The young priest, Kinsella, is initially opposed by the Abbot of the monastery, who tries to preserve his and his monks’ way of life. However, the Abbot eventually recognizes the need for—and inevitability of—change. The novel comes to a head when a confrontation between the Abbot and a senior monk, Matthew, nearly undermines the structure of the monastery. The Abbot is plagued by his own doubts in matters of faith. The novel ends on an ambiguous note as the Abbot prays for the first time in years, but in the face of the abandonment of their traditional way of life.
All I recall from the book & movie is that the Martin Sheen character was a sort of inquisitor (apostolic visitor?) to set to monks right & he practised yoga rather than an Catholic prayers. Or at least those are my 30-yr memory.
The idea of a new edition w/ study queries sound interested.