The article considers the universal metaphysical model of the relation of God to the world and man which L.P. Karsavin developed in all his works and which can be quite reasonably called mystical pantheism. According to this model, the world and man are the limited embodiment of God in the realm of Nothing, which spontaneously arises in God himself. It is shown that this model underlies the philosophical doctrine of Nicholas of Cusa. Analysis of the Christian gnostic treatise of the II century “Gospel of Truth” shows that it contains the earliest version of the mentioned metaphysical model. The article analyses the image of Jesus Christ in the concept of mystical pantheism expressing the universal aspiration of all personalities and the whole world back to the fullness of divine being. It is in this way that Jesus Christ is understood in F.M. Dostoevsky’s handwritten sketch of 1864, which suggests that in his philosophy Dostoevsky also developed a model of mystical pantheism.