| 2 Doctrine of Monotheism


The major disbelief (al-Kufr al-Akbar)

The major disbelief (al-Kufr al-Akbar) invalidates the faith (Imaan), makes its committer leave Islam, makes the eternal abode in the fire imperative, and deprives the person from receiving the intercession of the intercessors. The major disbelief occurs due to creedal defects, apostatising statements and deeds, unsurety, doubt, giving up faith, turning away from it or arrogance in its regard. [25] Al-Imaan: Haqeeqatuh, Khawaarimuhu, Nawaaqiduh 'Ind Ahl as-Sunnah, Abdullah al-Atharee, p;245.

This disbelief is of kinds, which are as follows:
1. Kufr due to denial: That entails believing that Messengers (peace be upon them) lied.  Anyone who denies them in terms of what they brought externally or internally, then he has committed disbelief (Kufr).

The proofs for this are as follows:


Proofs:

Allah, the Exalted, states, “And mention when We said to the angels, "Prostrate before Adam"; so, they prostrated, except for Iblees. He refused and was arrogant and became of the disbelievers.” Al-Baqarah: 34 Allah, the Sublime, also states, “And, although their hearts were convinced the signs were true, they still denied them wrongfully and arrogantly. See then what was the end of the corruptors!”  An-Naml: 14

3. Disbelief of doubt (Kufr ash-Shakk): That is unsurety and the state of not being totally convinced about the truthfulness of the Messengers. It is also known as disbelief based on assumption (Kufr ath-Thann), which is the opposite of certainty and surety. 
Proofs:

Ibn Katheer states, “They stated, 'Indeed, we disbelieve in that with which you have been sent, and indeed we are, about that to which you invite us, in disquieting doubt,’ inferring that 'we do not believe in what you have brought because we have a strong doubt about it.’” [27] Tafseer Ibn Katheer, vol.4, p.481.

Proofs:

The Statement of Allah, the Exalted: “But those who disbelieve, from that of which they are warned, are turning away.” (Al-Ahqaaf: 3)
As-Sam’aanee says, “Allah’s statement, 'But those who disbelieve, from that of which they are warned, are turning away,’ means they are turning away like the disinclination of those deniers who reject.” [28] Tafseer as-Sam'aanee, vol.5, p.148.

5. Disbelief of hypocrisy (Kufr an-Nifaaq): It refers to creedal hypocrisy which entails that one reveals belief but internally conceals disbelief. Amongst its proofs is as follows:

Allah’s statement, “And of the people are some who say, 'We believe in Allah and the Last Day,’ but they are not believers.” Al-Baqarah: 8 Ibn 'Atiyyah says, “Allah, the Exalted, negated belief from the hypocrites.” [29] Tafseer Ibn 'Atiyyah, vol.1, p.90.