Illness and suffering have always been among the gravest problems confronted in human life. In illness, man experiences his powerlessness, his limitations, and his finitude. Every illness can make us glimpse death.
Illness can lead to anguish, self-absorption, sometimes even despair and revolt against God. It can also make a person more mature, helping him discern in his life what is not essential so that he can turn toward what is. Very often, illness provokes a search for God and a return to Him.
Christ's compassion toward the sick and His many healings of every kind of infirmity are signs that "God has visited his people" (Luke 7:16). Jesus has the power not only to heal, but also to forgive sins; He has come to heal the whole man. His compassion toward all who suffer goes so far that He identifies with them: "I was sick and you visited me" (Matthew 25:36).
Often Jesus asks the sick to believe. He makes use of signs to heal: spittle, laying on of hands, mud and washing. The sick try to touch Him, for "power came forth from him and healed them all" (Luke 6:19). But He did not heall all the sick. His healings announced a more radical healing: His victory over sin and death. By His passion and death on the cross Christ has given a new meaning to suffering: henceforth, it can configure us to him and unite us with His redemptive Passion.
"Heal the sick!" (Matthew 10:8). The Church has received this charge from the Lord and strives to carry it out by caring for the sick as well as by praying for them. The Church has its own rite for the sick, attested to by St James: "Is any among you sick? Let him call for the presbyters [priests] of the Church and let them pray over him, anointing him with oil in the name of the Lord; and the prayer of faith will save the sick man, and the Lord will raise him up; and if he has committed sins, he will be forgiven" (5:14-15). The Church believes and confesses that among the seven Sacraments there is one especially intended to strengthen those who are being tried by illness; the Anointing of the Sick.
The Anointing of the Sick is not a Sacrament for those only who are at the point of death. Hence, as soon as anyone of the faithful begins to be in danger of death from sickness or old age, the fitting time to receive this Sacrament has arrived. One who receives this anointing and recovers may receive it again in the case of another serious illness. One who receives this Sacrament during an illness may have it repeated during the course of the same illness if his condition becomes more serious. It is fitting for the elderly whose frailty has become more pronounced, or for anyone of the faithful just prior to a serious operation. It is appropriate for family members to encourage a sick person to call for a priest to ask for this Sacrament.
The Anointing of the Sick confers the Holy Spirit, with His peace, courage, and strength, meant to lead the sick person to healing of the soul, but also of the body if it is God's will. Any sins committed are forgiven. (Because of this element of forgiveness of sins, only a priest may validly administer the Anointing of the Sick. (Lay persons functioning as hospital "chaplains" or "ministers to the sick," even if they use oil to "anoint" the sick, are not administering the Sacrament of the Sick.) The sick person receives the gift of uniting himself more closely with Christ's Passion, becoming a participant in the saving work of Jesus. If the person is near death, this Sacrament completes the holy anointings that have marked the whole Christian life at Baptism and Confirmation, preparing him to pass over into eternal life.
To learn more, refer to the Letter of James, chapter 5, and The Catechism of the Catholic Church, paragraphs 1499-1532.