When a man reaches the stage of devotion, he will be on a safe path. He is now a righteous and is placed under the guardianship of Allah. In this case, he will be immune from the temptations of Satan who has confessed that he will not harm the devoted ones. The word devoted ones has a general meaning. Therefore, everyone can reach the station of `i¥mah with endeavor, discipline and worship. Whatever is gained in the universe is due to Allah’s favor:
And whatever favor is bestowed on you it is from Allah. (16:53)
Allah is the True Agent
Man cannot possess anything without Allah having a part in it. Every being’s existence is contingent on the Necessary Being. Hence, if there is any perfection in man, it comes from Allah. Even the true agent behind teaching common knowledge is Allah:
He taught man what he knew not. (94:5)
We plough the land, sow the seeds and irrigate it but it is Allah who makes the seeds grow and come to fruition:
Is it you that cause it to grow, or are we the causers of growth? (56:64)
Self-Purification; Premise of Infallibility
Man can attain `i¥mah with discipline and self-purification. So `i¥mah is not solely for the Prophets and the Imams; rather when one is Prophet or Imam, he is infallible, but not the opposite.
Man can keep himself from error, sin, and oblivion by self-purification. He can do so before puberty so as to be ma`¥£m at puberty thanks to training and purification. Even those who have committed sins or errors can become ma`¥£m in the future with the same method. One who enjoys Divine training may reach a stage of `i¥mah where one will be immune from error in scientific issues:
If you are careful of your duty to Allah, He will grant you distinction. (8:29)
Distinction means to distinguish between what is right and what is wrong. Therefore, by observing piety and in the light of discipline received from the saints, man can become a distinguisher of good and bad. In that case, he will neither misunderstand nor acts wrongly. If it is said that a distinguisher may not know certain things, it is because like other virtues. `i¥mah too has certain ranks.
source : AHL AL-BAYT THE CELESTIAL BEINGS ON THE EARTH Allameh Hussein Ansariyan