Will be sin totally annihilated after Imam al-Mahdi’s rule has been established?
The most important motives for the human being's sinning are, on the one hand, his avarice in hoarding material wealth and, on the other hand, his sense of need for the goods of this world. If the human being possesses a sufficient amount of wealth, and a good social reputation, if his mentality becomes Divine-permeated, if the world and her goods are belittled in his eyes, and he thus reaches the certainty that all Divine promises are true and as such will certainly be fulfilled, regardless of the aversion of the enemies and their effort to obstruct their realization; if he reaches the certainty that there will be a resurrection, a reckoning, that paradise and what it holds are incomparably superior to the life of this world – in such a case, there will be no motive for sinning. This is especially true based on a few narrations to the effect that at the commencement of the Imam's revolution, Satan will be killed, hence putting an end to his tempting and decoying. (adapted from Tafsir al-Qummi)
Moreover, during that time, there will be innumerable obstacles in the way of sinning – such as, the inescapable and universal rule of justice, the healthy and secure environment, and the general rejection of corruption and sin by society. Therefore, there will remain very little motive for sinning, and at the same time, there will be obstacles in its way, which means that sin will be at its lowest ebb.
There are also numerous narrations in this regard, such as: Imam Ali bin Abī Tālib has thus described that era,
«...و يذهب الرّبا و الزّنا، و شرب الخمر و الرّياء، و تقبل النّاس على العبادة و المشروع و الدّيانة... و تؤدّى الأمانة، ... و تهلك الأشرار، و يبقى الأخيار...»[1]
"… Usury, illicit gender relationships, alcoholic beverages, and pretention will vanish. People will turn their attention to worship and obedience…; and they will righteously honor their trusts... The evil people will perish, and the virtuous will remain…"
Source: Office of Ayatollah Hādavī Tehrānī
[1] ‘Aqd al-Dorar, p. 159.