While all sects of Islam recognise the Qur'an, they differ in which other authorities they acknowledge; in particular the question of the Succession to Muhammad separates the Sunni, who acknowledge the elected Rashidun Caliphs and their descendants, from the Shia, who acknowledge the Imams or descendants of Prophet Muhammad; these two branches are then subdivided by their views on the further course of the succession. Shia fiqh differs with Sunni fiqh on not only political issues, but also important theological issues. Various attitudes towards Shias can be found among the worldwide majority Sunni community.
Among the more ecumenical fatwas was most important statement made on July 6, 1959 by Mahmood Shaltooth, the then rector of al-Azhar theological university in Egypt, one of the main centers of Sunni scholarship, stating the following:"The Shi'a is a school of thought that is religiously correct to follow in worship as are other Sunni schools of thought."
Shaykh Faraz Rabbani has noted that it is not the way of Sunnis to make blanket takfir of Shias. He writes:
...we only declare someone who denies something necessarily known of the religion to be a kafir--and this is not the case with common Shias. Someone who says 'There is no God but Allah, Mohammed is the Prophet of Allah' is a Muslim. Shia Muslims, who make this declaration of faith are therefore MUSLIM.
However, major Sunni scholars have declared the unbelief of Shias who hold certain beliefs. For example, Imam ibn Abidin, a source of authoritative fatwas for Hanafis writes:
There is no doubt in the disbelief (kufr) of those that falsely accuse Sayyida Aisha (Allah be pleased with her) of adultery, deny the Companionship of Sayyiduna Abu Bakr ( Allah be pleased with him), believe that Sayyiduna Ali (Allah be pleased with him) was an Imam... even if they believe in Allah, the last Prophet, and the perfection of the Quran (Radd al-Muhtar, 4/453).
According to Imam Ahmad Raza, the founder of the Barelwi-movement, most Shiites of his day were apostates because they repudiated necessities of religion. This includes, according to him, the following:
a) to believe that Qur'an is incomplete.
b) to call it 'book of `Uthman'.
c) elevate sayyiduna `ali karram Allâhu wajhah and other imâms above the prophets .
d) if these imâms are held to be higher than even one prophet .
e) to allege that Allâh was regretful after issuing a command and hence remorsefully, changed His earlier ruling.
f) to allege that Allâh didn't realize the wisdom of a certain ruling (or the lack of it) and when He realized it, He changed the rule.
g) to allege that RasûlAllâh practised taqiyyah in the course of his tabligh.
Those who hold the above and other such statements that amount to disbelief are kâfirs by ijmâ`a. All dealings with them are similar to those with apostates. it is in Fatâwâ Dhahîriyyah, Fatâwâ hindiyyah, Hadiqatun Nadiyyah: [aHkâmuhum aHkâm al-murtaddîn] they are to be dealt with as apostates.
Other scholars who have declared Shiites as deviants or apostates:
- Ibn Hazm — "Shia are not even Muslims", when Christians debating him brought a Shia book as reference.
- Ibn Taymiya — He considered Shiites more heretical than Jews, Christians and many polytheists. Noting contemporary circumstances, he considered Shiites more harmful to the Muslim community than groups such as the Crusaders and Mongols.
- Ibn Khaldoun — "astray people", "Shia are the source of all deviant groups in Islam history".
- Nizam al-Mulk — where he fully attacks the Rafida.
- Manzur Nu'mani — issued a fatwa in December 1987 declaring Shia kuffar (non-believers), which was endorsed by hundreds of prominent Deobandi scholars in India and Pakistan.
- Abd al-Aziz ibn Baz — Several of his fatwas denounced Shiites as atheists and apostates, and, among other rulings, forbade Sunni marriage to Shiites.
- Yusuf al-Qaradawi — After saying he had previously been misguided to pursue Sunni-Shia rapprochement, Qaradawi went on to condemn Shiites as heretics in several fatwas and praised virulently anti-Shia Saudi Wahhabi clerics for being “more mature and far-sighted” than himself in generally judging Shias.
- Ehsan Elahi Zaheer — Denounced the Shia as infidels and Zionist agents.
- Abdul-Rahman al-Barrak — In a "vicious" fatwa against the Shia he concluded with: "the Sunni and Shia mathhabs (beliefs) are completely contradictory and cannot be reconciled; the talk of Sunni-Shia rapprochement is utterly false."
- Abu Basir al-Tartusi — In his fatwa against Shia, he warned Muslims to "Interact with the Shii Rejectionists as you would with a person whose very existence is full of betrayal, treachery, fury and hatred against Islam and Muslims!"
- Ali al-Khudair — In his Fatwa fi l-Shi'a, he says: "What we have today are the Rafidis [i.e., Twelvers], the Batini Isma'ilis, the Batini Nusayris, and the Batini Duruz. These four groups are the ones who deify the Al al-Bayt [i.e., the family and descendants of the Prophet Muhammed], they seek their intercession and are the worshippers of graves (quburiyyun). So these [people] are infidel polytheists (mushrikun kuffar) and are not Muslims. There is no diffrerence [in status] between their scholars and followers (muqallidihim) or the ignorant among them (juhhalihim). They are all polytheists and are not Muslims and cannot be excused for their claim to be ignorant that they are worshipping other than God (la yu'dharan bi-l-jahl fi 'ibadati-him li-ghayr allah)."
- Imam Ash-Sha'bi — "The Rafida are the Jews of this nation. They hate Islam as the Jews hate Christianity. They embraced Islam, not because they longed for it or because they feared Allah, but because they detested the Muslims and intended to overpower them."
- Muhammad ibn Abd al-Wahhab — In one of his fatwas he accused Shiites of shirk (polytheism) because of their cult of the saints, which included the adoration of figures such as Ali and Husayn and the veneration of tombs and shrines.
- Shah Waliullah Dehlawi — He believed that the Shia interpretation and practices of Islam should be discarded, since they greatly misguide people.