vatican.va/archive/ENG0015/__P2I.HTM
Death
1006 "It is in regard to death that man’s condition is most shrouded in doubt."565 In a sense bodily death is natural, but for faith it is in fact "the wages of sin."566 For those who die in Christ’s grace it is a participation in the death of the Lord, so that they can also share his Resurrection.567
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. That aspect of death 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:
Remember also your Creator in the days of your youth, . . . before the dust returns to the earth as it was, and the spirit returns to God who gave it.568
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.**569 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.570 “Bodily death, from which man would have been immune had he not sinned” is thus “the last enemy” of man left to be conquered.571