The goal of this paper is to highlight the most recognizable effects of The Norse mythology and Christianity on his work, to focus on what kind of alternative genesis he created in The Silmarillion and how the sub-creation works in the beginning of his fictional past. My arguments will stand for the important similarities between ancient northern mythology and Tolkien's stories; and for the fact that Christianity had an important role in his life, which is reflected in the creation story of The Silnarillion.