Two great authors of children's fantasy literature, J. K. Rowling, and C. S. Lewis contributed significantly to the development of the genre by writing their two series of novels. The Chronicles of Narnia and the Harry Potter series offer the readership worlds full of magical creatures and thrilling events. The main topic of both series is the constant altercation between good and evil, however, the aim of this thesis is to consider the religious aspect of both series or the lack of one. In the introduction, the author poses various questions whose goal is to prepare the reader for the topic. After the short introduction about the authors of the series, a few theoretical aspects regarding the series are briefly reviewed. One of the aspects is the difference between religion and faith, which has earned its own passage due to its complexity. The chapter on children's literature offers an overview of the history of children's literature in general, focusing more on the fantasy in children's literature. Later chapters present both series and their position in children's literature, while at the same time they offer short summaries of each sequel in both series. Before the detailed examination of foregrounding and avoidance of religious aspects and symbols in both series, the third chapter offers an overview with the table of all the similarities worth mentioning between the series. Due to the large readership, there is a certain number of controversies that surround both series, and they are attended to in the fourth chapter. The final one offers the conclusion on the topic, which, due to the evidence provided throughout the thesis, claims that both series feature religious aspects. However, the nature of those religious aspects and their usage in the novels differ.