The uniting of the sick person to the passion of Christ, for his own good and that of the whole Church.
By uniting ourselves more closely to God through our sufferings, we receive the grace of Christ. Our suffering joins us to the Cross of Christ, and it contributes to building up the people of God.
The strengthening, peace, and courage to endure in a Christian manner the sufferings of illness or old age.
When Anointing of the Sick is given, we always hope that the person will be physically healed of any illness. But the primary effect of Anointing of the Sick is a spiritual healing. The sick person receives the Holy Spirit’s gift of peace and courage to deal with the difficulties that come with serious illness.
The Holy Spirit renews our faith in God and helps us fend off the temptations of the Devil to be discouraged and despairing in the face of suffering or death.
Anointing of the Sick completes our identification with Jesus Christ that was begun at our Baptism. The grace and power of the Sacrament fortify us in our final struggles before we die.
"In addition to these there is also a seventh [sacrament], albeit hard and laborious...In this way there is fufilled that too, which the Apostle James says: 'If then, there is anyone sick, let him call the presbyters of the Church, and let them impose hands upon him, anointing him with oil in the name of the Lord; and the prayer of faith will save the sick man, and if he be in sins, they shall be forgiven him.'" Origen, Homily on Leviticus, 2:4 (A.D. 244).
this oil...for good grace and remission of sins, for a medicine of life and salvation, for health and soundness of soul, body, spirit, for perfect strengthening." Serapion of Thmuis, Anaphora, 29:1 (A.D. 350).