Sin and death are the roots of evil which brought about eternal death which is separations from God. So, Christ came primarily to conquer sin and death. By his death on the Cross in obedience to the Father and his resurrection he conquered sin and death. He did not abolish temporal suffering but gave meaning to our sufferings. (Pope John Paul II, Salvici Doloris, Feb. 11, 1984) Suffering has a purpose in life. Through suffering God is reminding us to live a life according to his will because life is short followed by judgment.
St. Paul writes: "Now I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking in the afflictions of Christ on behalf of his body, which is the church." (Col. 1:24)
What does St. Paul means when he states that our sufferings is "filling up what is lacking in the afflictions of Christ"? This means that when we accept suffering in union with the Passion of Christ, we can remit the punishment our sins deserve either for ourselves or others. Our suffering does not gain the forgiveness of our sins because only God can forgive our sins, if we repent. Suffering in Christ will shorten or even eliminate our state of purification after death. A suffering which a martyr endures will certainly wipe away all his sins and suffering due to his or her sins because it is an expression of their great love of God.
Concerning the Sacrament of the Anointing of the Sick we read the following the Catechism of the Catholic Church: "By the grace of this sacrament the sick person receives the strength and the gift of uniting himself more closely to Christ's Passion: in a certain way he is consecrated to bear fruit by configuration to the Savior's redemptive Passion. Suffering, a consequence of original sin, acquires a new meaning; it becomes a participation in the saving work of Jesus." (#1521) Consequentially, this sacrament removes venial sins and all punishment due to sin. If a person is unable to confess serious sin due to his weakened condition, the anointing also removes serious sin.
Anointing of the sick has also positive aspects as specified in the Catechism, "The first grace of this sacrament is one of strengthening, peace and courage to overcome the difficulties that go with the condition of serious illness or the frailty of old age. This grace is a gift of the Holy Spirit, who renews trust and faith in God and strengthens against the temptations of the evil one, the temptation to discouragement and anguish in the face of death. This assistance from the Lord by the power of his Spirit is meant to lead the sick person to healing of the soul, but also of the body if such is God's will." (#1520)