The mere fact that sin brings darkness must act unfavorably on bodily health. But when you remember that it separates man from God, the Source of life, and places man in disharmony with all laws acting in himself and in nature, then one must marvel how a sinner remains alive after sinning. This is the mercy of God, Who awaits repentance and conversion. Consequently, a sick person must rush first of all to be cleansed of sins and make peace with God in his conscience. This paves the way for the beneficial action of medicine. They say that there was one distinguished doctor who would not begin treatment until the patient had confessed and received the Holy Mysteries; and the more serious the disease, the more urgently he insisted upon this.
~Saint Theophan the Recluse