Eschatology (from the Greek ta eschata) literally means “the study of the last things.” It is a branch of theology that focuses on what has traditionally been called the Four Last Things, individually (death, judgment, heaven, hell) and universally (Second Coming of Christ, the resurrection of the dead, general judgment, the end of the world).
Human beings will experience, individually, the end of their own earthly life, and then, at a time known to God alone, the entire world (and physical universe) will meet its own end as well. The first ‘four last things’ occur when the person dies and the second ‘four last things’ happen at the end of the world. Each man and woman on earth, since the time of Adam and Eve, has or will experience death. Genesis
2:17 states that death is the penalty for sin, and since we have all sinned in one way or another, then all of us must die someday (Romans 5:12).
What happens after death? Particular judgment occurs immediately after the person dies. Philosophically and theologically, once the immortal soul leaves the mortal body, there is death. The dead body begins to incur rigor mortis and finally putrefaction (decay and decomposition). The soul, however, since it is immortal, cannot stay on a physical place like Earth without a physical body. Particular judgment happens instantaneously when death occurs. Jesus Christ appears, but not as Savior and Redeemer as He did on earth on Good Friday; rather, He appears as Judge of the living and the dead. The dead person is judged by the life he or she lived on earth.
Avoiding sin (keeping the commandments) is only half the mission every human person is given by God. The other half is doing good. What did the person do in life? It is not enough to say, “I did not kill,” or “I did not steal,” or “I did not commit adultery,” even though avoiding those things and any sin for that matter is a good thing. Matthew 25:31–46 tells the parable in which Jesus is compared to a shepherd with a flock of sheep and goats. The sheep are placed on the right, and the goats on the left. Those on the right go to heaven, those on the left are sent to hell. What determines if you are a goat or a sheep? That same passage explicitly shows that the sheep are those who took care of others (friends, neighbors, and strangers), while the goats are those who ignored the needs of others. Jesus says to the goats in this section of Matthew’s Gospel, “‘I was hungry and you gave me nothing to eat, I was thirsty and you gave me nothing to drink, I was a stranger and you did not invite me in, naked and you did not clothe me, sick and in prison and you did not visit me.’ They also will answer, ‘Lord, when did we see you hungry or thirsty or a stranger or naked or sick or in prison, and did not help you?’ He will reply, ‘I tell you the truth, whatever you did not do for one of the least of these, you did not do for me.’ Then they will go away to eternal punishment, but the righteous to eternal life.”
Sins of omission, such as neglecting the corporal and spiritual works of mercy are incriminating evidence that you are a goat and will be placed on the left to be cast into hell. People often think their salvation is assured, so there’s no need to “do good” as long as they have faith and, at most, avoid committing sin. Matthew 25, however, mentions no quiz on what people believe; rather, they are judged on whether or not they have put faith into practice.
Catholicism teaches that at particular judgment, one of three verdicts occurs. One is the worst-case scenario: an evil and immoral person who has not only committed a mortal sin and is unrepentant, but has also neglected to help others. That person is condemned to hell. The other alternative is the best-case scenario; a good and holy person who has kept the commandments; lived a moral, virtuous, and holy life; and has consistently helped stranger and friend alike is rewarded with the joy of heaven.
A third or middle possibility is that the person is not bad enough to go to hell but also not good enough to go directly to heaven. Their sins have been forgiven on earth but there is still some attachment to sin (they have fond memories of some of their sins). They need some cleansing (purgation); hence, they go to purgatory before going to heaven. Everyone in purgatory is absolutely guaranteed to go to heaven, but they must first remove any and all attachment to sin before walking through the pearly gates.