From: Les Keyser, Martin Scorsese, Twayne Publishers: New York (1992), pages 140-141:
[Scorsese's] next picture was the dream project of his life, his adaptation of Nikos Kazantzakis's 1954 novel The Last Temptation of Christ. Kazantzakis, a nonbeliever, had created controversy in Greece by limning an untraditional story of the Messiah in demotic Greek. Scorsese wanted to bring this populist existential Christ to the American people in his modern guise, not as a comforting Hallmark-card Jesus, sure of his powers, but as an unsettling, tortured Jesus, unsure whether his inner voices are divine or demonic, and torn between his love of the flesh and his need for the divine.
Kazantzakis, his translator Peter Bien admits, did not believe in any traditional God; nor did he believe in a spiritual afterlife. Kazantzakis, Bien observes, felt that this world would "somehow, through its own dematerialization, produce its own materialistic renewal in another cycle"; in his sotry of the Messiah, Bien argues, Kazantzakis attempted to assist our inevitable evolutionary transformation. Kazantzakis, like the Catholic philosopher Teilhard de Chardin, envisions a God-who-is-to-be, born of humanity's ascent to the divine, and in his prologue to The Last Temptation of Christ identifies his Messiah's struggles with the mystic destiny of civilization: "Struggle between the flesh and the spirit, rebellion and resistance, reconciliation and submission, and finally--the supreme purpose of the struggle--union with God: this was the ascent taken by Christ, the ascent which he invites us to take as well, following in his bloody tracks."
Kazantzakis's themes, the needs for salvation and transformation, the struggle between flesh and spirit, and the choice between rebellion and reconciliation, parallel Scorsese's interests from Mean Streets through Taxi Driver and Raging Bull.