The study of the history and the course of Ijtihad in Islam indicates that Ijtihad was carried out with two approaches; the first approach of Ijtihad was to understand and interpret Islam. Following the advent of Ijtihad, in order to understand the word of Islam, Ijtihad was used to prove the legitimacy of Ijtihad itself and to give reasons for the legality of Ijtihad and determine the value of opinions based on Ijtihad. The issue was whether Ijtihad is possible to achieve the truth or not. Also, the other question was that in which fields Ijtihad is allowed. In this way, the possibility or impossibility of knowing about the truth of the opinions based on Ijtihad was raised; this concept can be called Ijtihad in Ijtihad. It is through Ijtihad in Ijtihad that mujtahids can judge about the truth or falsehood of Ijtihads of other mujtahids. Some of the Ijtihads of the Mujtahids have been described as deviation and the Mujtahids have been described as blasphemers, corrupted, wicked, aberrant and misled while the nature of Ijtihad necessitates the existence of different and dissimilar opinions and it is possible that the Ijtihads of the Mujtahids who have been attributed by those descriptions, be true, and this lack of commitment to the right to express different ideas and creation of different Ijtihads has led to the emergence of extremism. Therefore, the way to fight against extremism is commitment to Ijtihad, i. e. the right to have a different theory in the Islamic society.

The issue of takfir and Tafsiq, which is the result of jurisprudential and theological differences among Muslims, has long been the cause of bloody conflicts between followers of Islamic religions. This religious damage extends beyond the Muslims to the Shiite Imams, who themselves embodied Islam. Despite the many narrations from the Holy Prophet and the Shiite Imams (as) about the prohibition of takfir and unnecessary Tafsiq, the history of Islam has witnessed takfirs and Tafsiqs that have left unpleasant results. Even today, the Islamic world is witnessing an emerging sect with the slogan of Salafism, which makes a not-so-new claim of takfir of other Islamic religions and they call any religion other than that of themselves non-Muslim, while there is no basis in the Qur'an and Sunnah for such a takfir. This study has examined the position of Takfir in the tradition of the Shiite Imams (AS) in order to clarify the status of Takfir in the light of the tradition of those nobles who are the interpreters of the words of God and the successors of His Messenger.

In the history of Islamic though, faith and gnosis -Iman va Ma’rifat- are two key and controversial theological concepts, having always been subject the argument. Some important theological problems such as excommunication and calling one profligate-Takfir va Tafsiq-, principle of rational goodness and badness -Hosn va Qobh-i Aqli- are obviously consequences of diversity in definition of these two concepts. Among Muslim scholars, Sufis based on their own world- view, have had a particular conception towards them. Sufis attractive attitude stimulates us to investigate their definition of Iman and Ma’rifat.So, the present paperis an attempt to survey them semantically and examine their relation with each other and the impact of reseating on faith according to Sufis’ words and views. Eventually the resemblance of Sufis’ viewpoint with the approach of the fideists and reformed epistemologists have briefly been presented.