According to Gregory Palamas, when a person attains to theoria of God he manifests spiritual health, for theoria “is the only proof of a soul in good health” (Palamas, The triads), since it is an outcome and deifying state in which the soul’s three faculties function as originally intended by God – naturally. Perfect spiritual health “is the result of the consolation that comes from tears, and creates the essential preconditions for the longing for marriage of the person with Christ the Bridegroom. This marriage is the vision of the uncreated Light and man’s transformation into light” (Met. Hierotheos, The science of spiritual medicine, pp. 86-87). Spiritual illness, therefore, consists of man’s “inability to see the Light, his lack of vision of the uncreated Light” (ibid.), making these a spiritual illness, spiritual abyss, because spiritual health comes through purification of the heart, the illumination of the heart of the soul, the nous; the outcome of which is the vision of God as Divine Light.
Spiritual illness results from a person’s soul being dominated by the passions, which occurs when the heart of the soul is darkened, deadened, or dead through sin. When a person’s soul is spiritually ill, “the nous becomes entangled with the rational faculty and the passions . . . It is, however, clearly distinct from the rational faculty when it functions as was intended by the energy and grace of God, and when the abnormalities concealed in human nature are revealed and healed” (Romanides, in Met. Hierotheos, The science of spiritual medicine, p. 89). According to Hierotheos, it is this anomaly of confluence of the heart of the soul with the rational faculty, the passions, and the environment, that is the cause of many psychological problems.