Ritual of the Holy Assumption

Through the Ritual of the Holy Assumption, Walter Sullivan was able to become the 11th Sacrament by crucifying himself in Room 302's storage room and continue to live as a ghost in his own "Otherworld". The exact workings of the ritual are unknown; however, when Henry Townshend discovers Walter's corpse in Room 302, he also finds some of the cult's sacred objects, such as the Obsidian Goblet and the White Chrism, giving the possibility that they may be required for the ritual. To prepare for the ritual, ten hearts, or ten sacrifices, are also required; these are also found inside the storage room's refrigerator.

The Ritual of the Holy Assumption is also mentioned in Note #82 of the Ivory Testament in Silent Hill: Book of Memories.