The Last Things, also known as eschatology, is the part of Catholic theology that is concerned with death, judgment and the final destiny of the human soul in heaven or hell.
Death
Is the moment in which the soul and body are separated at the moment one’s earthly life has expired. Death is also the punishment determined by God as a consequence for the sin of Adam as stated in Genesis 2:17 and Romans 5:12. Following the moment of death, the soul is met with his/her particular judgment and is immediately sent to heaven, purgatory or hell.
Judgment
Particular
Is the judgment that takes place immediately following death, which is attested to throughout the New Testament (Luke 16:22, 23:43; Acts 1:25) and is the teaching of the Council of Florence held in 1431-1449 (Denzinger, Enchiridion, no. 588) which addresses the souls expedient entry into heaven, purgatory or hell. It is during this judgment where the soul will experience the most intense scrutiny for everything he/she has done, spoken or thought during its earthly life.
General
The general judgment will occur at the same time and place when all men shall stand together before the tribunal of the Divine Judge, and all will learn and receive their final sentence.
Heaven
Heaven is both a place and a state, as it says in the scriptures that Our Lord Jesus Christ came down from heaven, and ascended into it. It is a state, for example, when the Blessed Virgin Mary appears to men, she doesn’t leave heaven, but rather she carries it with her in the state of her soul. This is how good and holy men and women on earth can experience a foretaste of heaven, through the peace and joy they possess in their hearts.
Those rewarded with heaven are the souls of the just who die in a state of sanctifying grace, and if necessary, who have been purified in purgatory from all venial sin and debt for temporal punishment. Those who have attained heaven now see God face-to-face, as St. Paul says, “At present, we are looking at a confused reflection in a mirror; then, we shall see face to face; now, I have only glimpses of knowledge; then, I shall recognize God as he has recognized me” (1 Cor. 13:12).
Purgatory
Proof for the existence of purgatory is cited in both the Old and New Testaments (cf. Isaiah 4:4; Malachi 3:3; 2 Maccabees 12:44-45; Matthew 5:22, 26; 1 Cor. 3:11-15; Revelation 21:27).
It is believed that purgatory is a middle state where souls who are destined for heaven are detained and purified of the guilt of all temporal punishment due to their venial sins or mortal sins that have already been forgiven. They can no longer merit any grace as their time for meriting has passed with their death on earth, however the suffering souls in purgatory can be assisted by the prayers of the faithful on earth.
The belief in purgatory has been a continuous teaching of the church through the millennia, from St. Paul, to the early Church Fathers and Doctors of the Church, and was given a solemn definition at the Council of Trent:
There is a purgatory, and the souls there detained are assisted by the suffrages of the faithful, but especially by the most acceptable sacrifice of the altar.
Hell
In the sacred scriptures, Our Lord speaks of the punishment of hell in at least 15 instances, and refers to it as “a place of torment,” “an unquenchable fire,” etc.
Those souls who die in a state of unrepented and unforgiven mortal sin are punished in hell and are deprived of the vision of God (beatific vision). Not only are they deprived of the beatific vision, but they must endure dreadful torments as punishment for their sins committed in life.
God continually calls us to repentance and it is through his sacrament of penance (reconciliation/confession) that we are loosed from the bonds of sin and are restored to a state of grace. While the Lord stands as an anxious and loving father awaiting the return of his prodigal sons and daughters, the sinner who persists in his sin will have only himself to blame when he is condemned to hell at his particular judgment.