As in his other novels, Williams is more concerned with the conflict between good and evil than with the depiction of everyday life. To establish this conflict, he uses many of the conventions of the fantasy genre.

The title, All Hallows’ Eve, suggests the ancient Celtic festival of Samain, when it was believed that the gates between the spirits of the living and the dead opened and allowed easy passage. Williams accepted the Christian transformation of this holiday. In the tradition of Saint Augustine’s The City of God (413-427), the “hallows,” the souls of the blessed dead, take on the form of “the Acts of the City” and support Lester when Simon attempts to destroy her. The world of the dead, in fact, seems more vital and alive than drab wartime London. Although Betty is Simon’s daughter, she is saved from his power both by Lester and by the “wise waters” of baptism, the christening given to her by her nurse.

Williams, who was a member of the Mystical Order of the Golden Dawn, also uses magic in the novel. Simon is both a version of Simon Magus (Acts 8:9-24) and the Antichrist. Williams insists that Simon is a Jew not because he is being anti-Semitic but because he is setting Simon in contrast to “that other sorcerer of his race, the son of Joseph, . . . Jesus Bar-Joseph.” The scenes of conjuring and magical creation seem authentic but avoid the melodramatic excess of much gothic fiction.

Williams also uses Dante Alighieri’s The Divine Comedy (c. 1320) in his fiction. Lester moves beyond Hell and through Purgatory. Readers see a hint of Paradise in the martyr’s blood and mystic rose of the last chapter, which draws on Dante’s portrayal of the blessed in Paradise. The first chapter may owe something to Dante’s spiritual autobiography, his La vita nuova (c. 1292; The New Life, 1867).

The confrontation between good and evil, like the contrast between Jonathan’s two paintings of the blessed and the damned, the light and the dark, emerges only through gradual revelation rather than melodramatic announcement. Readers come to recognize that although Simon preaches love, his only interests are himself and the establishment of his own complete power. He sires Betty not out of love or even lust but instead out of his desire and need to create an instrument he can use for his own ends. Simon insists, “I am the one who is to come, not Hitler!” To this end, he has created images of himself that appear in Russia and China. These unreal shadows, parodies of the Christian trinity, finally return to destroy him.

In contrast to Simon’s joyless self-absorption, the novel presents the self-sacrifice of Lester, the radiant forgiveness of Betty, and the love that Richard and Jonathan feel for these two remarkable women. As Williams put it in an essay on “The Redeemed City” (1941), “There is no final idea for us but the glory of God in the redeemed and universal union—call it Man or the Church or the City.”