Major Resurrection - The day of Reckoning
"Nay, I swear by the Day of Resurrection." Qur’an (75:1)
Believing in this day is one of the foundations of the Islamic faith. The Noble Qur’an makes very many references to it. All the prophets of Allah reminded their peoples about this monumental day. Disbelievers normally deny the day of resurrection, claiming that their existence in this temporal life is purposeless. It is only the time (age) which turns a newborn to a young and then to an elder person - who eventually perishes upon death. No spirit. No life after death. How a dead person who turns to dust and decayed bones can be brought back to life? They wonder.
In Islam, this day has many names. The Qur’an gives a number of characteristics to it. It comes suddenly, making the disbelievers really wonder... A nursing mother will be bewildered from her newborn. On that day, a man will flee from his brother, wife, and sons. Everybody will be regretful then. The believers would regret for not doing enough good to shield them from the horrors of that day. The disbelievers will be regretful for being caught in a surprise.
Some 4000 years ago, Abraham once asked Allah to show him how He resurrects the dead. Demonstrating His Power to His close friend, Allah told him to do a little experiment. The Qur’an cites the story of cutting four birds into pieces, placing their flesh onto four mountains, then summoning them back.. All the four birds flew hastily back to Abraham, by the leave of Allah.
As a prophet, Abraham was naturally a believer. Developing spiritually, he became a Messenger. The Qur’an lists him among the five envoys of Allah who delivered universal messages. By conducting above experiment, he wanted to elevate his certainty (about Allah's Power in resurrecting the dead). After completing Allah's trials, Abraham attained the status of an Imam.
Like Moses and Jesus, Abraham foretold the coming of Muhammad. The Prophet Muhammad, in turn, foretold about the coming of the Mahdi. This will occur just before the day of resurrection. The seal of the Prophet's certainty about the coming of Imam Mahdi was no less than that of Abraham's certainty about the Judgment day.
Source: Universality of the Mahdi’s Mission
The Existence of the Mahdi is certain
Imam Mahdi in Ghadir Sermon
Supplication and avoidance of sins: keys to heartfelt relations with the Imam
Differences between a Monarchic and Islamic System of Government
The Mahdi in Muslim Traditions (Part 2)