The events before the end of the world are described in a number of places in holy Scripture: the 24th chapter of Matthew and parallel places in the other Gospels; most of the book of the Apocalypse, especially chapter 8 and onwards; the second chapter of II Thessalonians; II Peter, chapter 3; several chapter of the book of Daniel; and other passages.
The Apocalypse describes these events in a series of visions: some bright and positive, relating to the fulfillment of God's justice and the salvation of His chosen ones; and some dark and negative, relating to the terrible plagues that will come on earth for the sins of mankind. Sometimes we today emphasize the dark and negative side, seeing the increase of evil around us; but that comes from our faintheartedness and worldliness—we must look at the whole picture.
As the time of the end of this world comes near, it is true that there will be a time of tribulation such as the world has never seen [Matt 24:21]: there will be famines, plagues, earthquakes, wars and rumors of wars, persecutions, false prophets and false Christs, and the love of many (including Christians) will grow cold. But at the same time the Gospel will be preached to all nations, and those who endure to the end with the aid of Christ will be saved.
The evil and false religion in the world will culminate in the reign of Antichrist, a world ruler who will seem to bring peace out of the world disorder and will seem to be Christ come again to earth, reigning from the restored Temple in Jerusalem.
But there will be those who see through the deception. In particular, two Old Testament prophets who did not die will return to earth—Elijah to convert the Jews, and Enoch to preach to the other nations. The short reign of Antichrist—only three and a half years—will end in new disorders and wars, in the midst of which Christ Himself will come from heaven, preceded by the sign of the Cross, and this world will be consumed by fire and totally renewed, at the same time that the bodies of the dead will arise from the tomb and be rejoined to their souls in order to stand before God's final judgment.