The notion of “conscience” is one of the most ancient components of the axiological sphere, the central factor of a person’s moral consciousness. The phenomenon is closely linked with the features of the ontological status of man in the world. The authors present the concept of conscience in the philosophical and religious tradition and examine the key ideas of Immanuel Kant’s religious philosophy in connection with moral consciousness as the “voice of conscience”. The idea of heterodoxy and contradiction between Immanuel Kant’s religious philosophy and Christian religious and philosophical tradition is substantiated.