This is because if a person has passed his life in vandalism...

This is because if a person has passed his life in vandalism and treason he would be a suspect to people even if due to some unexpected revelation he could have purified his soul against further wrongdoing. People would never forgive or forget his past wrongdoings. They could even accuse him of hypocrisy. This affair is even more evident in the religious issues.

The texts of Shariah (the divine law) are not formed in such a way that a philosopher or a teacher could advance their case through reasoning. Rather Shariah is based on the heavenly inspiration and revelation with which man has become familiar in history. And in order for the followers of these leaders to accept and adopt such teachings and instructions, they should have perfect confidence in their religious leaders and in the revelations which they receive.

It is obvious that a religious leader with a dark past could not create such confidence[^3]. These two reasons not only lead us towards the infallibility of the Prophets but also confirm the fact that the Prophet's successors should be flawless and innocent like himself.

This is because the position of an Imam, contrary to what the Sunnites believe, is not a usual leading position; rather as we have previously emphasized[^4], an Imam's position is a heavenly and divine position and an Imam shares with the Prophet all positions (except for the position of prophethood and the receiving of revelation).

An Imam is the protector of religion and is the interpreter of the Holy Quran and the announcers of those heavenly commands which the Prophet did not have the chance to explain. Therefore, an Imam is the governor, the leader of Muslims, and the protector of their lives. He is also a heavenly instructor for Shariah. Such an individual should be equipped with infallibility.

This is because the commitment of any sin, either small or big nullifies the effects of education and does away with people's confidence altogether. [^1]: . Furthermore, to abstain from telling lies the sinner should at times confess to that fact that he has lied. And an loon and this happens. People would doubt his authority and would hate him. As a result he would face the previous problem i.e. lack of prestige and authority among people. [^2]: .

Observe the truth of speaker's expression and disregard, his personal characteristics in the recognition of right versus wrong. [^3]: .