Ismah in the context of "Twelver Shi'ism"

Twelver Shi'ism (Arabic: اِثْنَا عَشَرِيَّة, romanized: Ithnā ʿAshariyya) is the largest branch of Shia Islam, comprising about 85% of all Shia Muslims. The term Twelver refers to its adherents' belief in the twelve successors, referred to as Twelve Imams, and their belief that the last Imam, Muhammad al-Mahdi, lives in occultation (ghayba) and will reappear as "the awaited Mahdi" (al-Mahdi al-muntazar) alongside Isa al-Masih (Jesus Christ), son of Bibi Mariam (The Virgin Mary), in order to restore justice and peace.

Twelver Shi'as believe that the Twelve Imams are divinely appointed as both spiritual and political successors to the Islamic prophet Muhammad, and that they possess special knowledge and authority to guide the Muslim community. According to Twelver theology, the Twelve Imams are exemplary human individuals who rule over the Muslim community (Ummah) with justice, and are able to preserve and interpret the Islamic law (Sharia) and the esoteric meaning of the Qur'an. The words and deeds (sunnah) of Muhammad and the Imams are a guide and model for the Muslim community to follow. As a result, Muhammad and the Imams must be free from error and sin, a doctrine known as Ismah (literally 'protection') or infallibility, and must be chosen by divine decree, or nass, through Muhammad.

In Shia Islam, the Imamah (Arabic: إمامة) is a doctrine which asserts that certain individuals from the lineage of the Islamic prophet Muhammad are to be accepted as leaders and guides of the ummah after the death of Muhammad. Imamah further says that Imams possess divine knowledge and authority (Ismah) as well as being part of the Ahl al-Bayt, the family of Muhammad. These Imams have the role of providing commentary and interpretation of the Quran as well as guidance.

Ja'far ibn Muhammad al-Sadiq (Arabic: جعفر ابن محمد الصادق, romanized: Jaʿfar ibn Muḥammad al-Ṣādiq; c. 702–765) was a Muslim scholar, jurist, hadith transmitter and the sixth and last agreed-upon Shia Imam amongst Twelvers and Isma'ilis. Known by the title al-Sadiq ("The Truthful"), Ja'far was the eponymous founder of the Ja'fari school of Islamic jurisprudence. In the canonical Twelver hadith collections, more traditions are cited from Ja'far than that of the other Imams combined, although their attribution to him is questionable, making it hard to determine his actual teachings. Among the theological contributions ascribed to him are the doctrine of nass (divinely inspired designation of each Imam by the previous Imam) and isma (the infallibility of the Imams), as well as that of taqiya (religious dissimulation under persecution).

Al-Sadiq is also revered by Sunni Muslims as a reliable transmitter of hadith, and a teacher to the Sunni scholars Abu Hanifa and Malik ibn Anas, the namesakes of the Hanafi and Maliki schools of jurisprudence. Al-Sadiq also figures prominently in the initiatic chains of many Sufi orders. A wide range of religious and scientific works were attributed to him, though no works penned by al-Sadiq remain extant.

Ahl al-Bayt (Arabic: أَهْل ٱلْبَيْت, lit. 'people of the house') refers to the family of the Islamic prophet Muhammad. In Sunni Islam, the term has also been extended to all descendants of the Banu Hashim (Muhammad's clan) and even to all Muslims. In Shia Islam, the term is limited to Muhammad, his daughter Fatima, his cousin and son-in-law Ali, and their two sons, Ḥasan and Ḥusayn. A common Sunni view adds the wives of Muhammad to these five.

While all Muslims revere the Ahl al-Bayt, Shia Muslims assert that members of the Ahl al-Bayt are spiritual successors to Muhammad, possessing divine knowledge and infallibility. The Twelver Shiʿa also believe in the redemptive power of the pain and martyrdom endured by the members of the Ahl al-Bayt, particularly Husayn. Sunni Muslims, who do not believe in spiritual succession to Muhammad, only hold the Ahl al-Bayt in high regard.

The Twelve Imams (Arabic: ٱلْأَئِمَّة ٱلْٱثْنَا عَشَر, al-ʾAʾimmah al-ʾIthnā ʿAšar; Persian: دوازده امام, Davâzdah Emâm) are the spiritual and political successors to the Islamic prophet Muhammad in the Twelver branch of Shia Islam, including that of the Alawite and Alevi.

According to Twelver theology, the Twelve Imams are exemplary human individuals who not only rule over the community with justice, but also are able to keep and interpret sharia and the esoteric meaning of the Quran. The words and deeds of Muhammad and the imams are a guide and model for the community to follow; as a result, they must be free from error and sin (known as ismah, or infallibility) and must be chosen by divine decree through Muhammad.