Promotion of Knowledge and Ethics
Imam Mahdi’s reappearance is the day of endless torment for unbelievers while it is happiness and mercy for virtuous believers. In that era, people’s heart will turn kinder and their morality will be improved. All material thoughts will focus on spirituality.
According to the Holy Prophet Muhammad (PBUH), all people obey and worship Allah and do their best in performing religious practices. In other words, when one perfect and immaculate human being, who is able to teach people to behave wisely, rules over the world, people naturally welcome worshipping of Allah and all moral corruptions will be removed. In addition, if a few disturb and bother others and prevent them from thinking wisely and behaving morally, they will be advised in the first place, else they will be removed. 
Commenting on the same issue, Imam Sadiq (A.S) says: “There are 27 letters of knowledge. The knowledge that has been revealed till date through all the Prophets (PBUT) is the interpretation of only two of those letters. When our Qaem (AJ) will rise, then Allah will reveal the remaining 25 letters and will add to the existing two letters. In this way knowledge with all 27 letters will become complete.”
This Hadith clearly defines the rapid scientific progress of Imam Mahdi’s movement in his era. It also refers to the most powerful and excellent education and training system in that era. Therefore, in that era, the scientific changes and developments will be much more than the previous eras.
Dealing with Offenders
In every society, there are some people who unknowingly commit sins and eventually they are warned through ‘enjoining good and forbidding evil’ which simply convince them stop committing evil deeds. However, there are some others who notice their mistakes only through strict and decisive implementation of divine commandments. Imam Mahdi’s reappearance is the outset of spring for the faithful and winter for wrongdoers.
Quoting the Holy Prophet Muhammad (PBUH), Imam Javad (A.S) states: “He will implement the rules and divine commandments.” 
Translated by: Sadroddin Musawi
1. Al-An’am Surat (124)
2. Bahar al-Anvar, Vol. 52 , P. 336
3. Ibid, Vol. 52, Chapter 27.