In this article I show that Dostoevskij criticized traditional Christianity, and that for him the authentic teaching of Christianity concerned the unity of man and God, the existence in man of a divine "dimension," the opening of which allows man to become an absolute being. In the context of this understanding of man and God the concept of "joy" is an important one. This concept includes, on the one hand, the fullness of earthly human life (this aspect of joy is expressed by Dmitri Karamazov) and, on the other hand, the transformation of man and of all earthly being into an absolute and divine state (this aspect of joy is expressed by Kirillov and the elder Zosima). Dostoevskij's philosophical outlook appears to be a development of a well known philosophical tradition, mystical pantheism.