Nicolas Poussin, “Extreme Unction” c. 1638-1640.

1007. Death is the end of earthly life. Our lives are measured by time, in the course of which we change, grow old and, as with all living beings on earth, death seems like the normal end of life… [D]eath lends urgency to our lives: remembering our mortality helps us realize that we have only a limited time in which to bring our lives to fulfillment…

1008. Death is a consequence of sin. The Church’s Magisterium, as authentic interpreter of the affirmations of Scripture and Tradition, teaches that death entered the world on account of man’s sin. Even though man’s nature is mortal, God had destined him not to die. Death was therefore contrary to the plans of God the Creator and entered the world as a consequence of sin. Bodily death, from which man would have been immune had he not sinned is thus the last enemy of man left to be conquered.

1009-1010. Death is transformed by Christ… The obedience of Jesus has transformed the curse of death into a blessing. Because of Christ, Christian death has a positive meaning: “For to me to live is Christ, and to die is gain” (Phil 1:21). “The saying is sure: if we have died with him, we will also live with him” (2 Tim 2:11). What is essentially new about Christian death is this: through Baptism, the Christian has already “died with Christ” sacramentally, in order to live a new life; and if we die in Christ’s grace, physical death completes this “dying with Christ” and so completes our incorporation into him…

1011. In death, God calls man to himself. Therefore the Christian can experience a desire for death like St. Paul’s: “My desire is to depart and be with Christ” (Phil 1:23). He can transform his own death into an act of obedience and love towards the Father, after the example of Christ. As St Teresa of Avila prayed: “I want to see God and, in order to see him, I must die.” Similarly, at her death, St Therese of Lisieux reflected: “I am not dying; I am entering life.”

1013. Death is the end of man’s earthly pilgrimage, of the time of grace and mercy which God offers him so as to work out his earthly life in keeping with the divine plan, and to decide his ultimate destiny. When the single course of our earthly life is completed, we shall not return to other earthly lives: “It is appointed for men to die once” (Heb 9:27). There is no “reincarnation” after death.

1014. The Church encourages us to prepare ourselves for the hour of our death… Thus, we ask the Mother of God to intercede for us “at the hour of our death” in the Hail Mary. We can also entrust ourselves to St. Joseph, the patron of a happy death.

Selections from the Catechism of the Catholic Church.