Question: What beliefs are “bid’ah” but do not take one outside the fold of Islam, as opposed to the clear kufr of the falasifa and other sects? If a particular belief is against the sound beliefs of the Ahl al Sunnah wal Jama’ah, by what criteria to we judge that this belief either takes one out of Islam, or takes one out of the fold of Ahl al Sunnah only, but would still leave the person who holds this belief a Muslim?
This is a long discussion with much divergent opinion, and that I will provide great detail later on because of its importance. Briefly, Maalik said that all deviants are kuffaar in one of his sayings. An example of where they differed in takfir is regarding the one who thinks Allah will not forgive his sins, but surely will punish him, while not denying its intellectual possibility. Where they agreed is where the belief was in clear contradiction with tawhid, or implied a flaw, such as believing that Allah is physical, or has a limit, or shares His attributes with something else, or that there is something else that creates. Al-Tahaawi mentions a number of things, but for now, to deny any of the following would be plain kufr:
- Know that Allah is Necessarily Existent without a beginning or an end; non-resemblant to anything or anyone in any sense; Self Existent and does not need a specifier for Him or His attributes, or something to be in; One without a partner, part or like in His Self, attributes or actions.
- Only He can create, and all that happens is according to His Will and Predestination.
- Sound reason tells us that He must be attributed with the Power to bring anything possible into existence, the Will to specify how it is to be, and Knowledge of all that is now, has been in the past, and will be in the future, as well as all that must be, cannot be, or may be.
- His attribute of Life is without beginning, end, body, soul, change or development.
- He must be All-Hearing and All-Seeing, not by ability, but by necessity; without instruments, such as eyes or ears; or needs, such as sound waves or light rays; or events, such as hearing or seeing one thing and then another.
- He must also have Speech that is not created and is therefore not language, sounds, letters, sequence, or a capacity; for all such attributes must have a beginning, and therefore a creator.
- It is impossible that Allah be attributed with the opposites of any of the above, such as being a body, in a place, or having a limit or a weakness, such as ignorance, death, deafness, blindness or speechlessness.
- It is possible, however, that Allah creates anything that can exist, or leaves it. He is the creator of all beings, things and actions and thus the Absolute Owner of everything.
- It is impossible that He could be unjust or unfair, as He has no creator, and therefore no judge. In addition it would be plain kufr to say that it is possible for Prophets to lie, or that they might commit mean acts, such as desiring other men’s wives, or even contemplating adultery.
Authored by Shaykh Abu Adam al Naruiji
Sunni Answers 
According to Ibn Juzayy al-Kalbi (the person given the most credit for summarizing the various views in the Maliki school and also outside of the Maliki school), the acts are:
a) Negating that Allah has Lordship over His creation.
b) Negating that Allah is one in His Entity, attributes, and actions.
c) Worshiping another entity along with Allah (shirk).
d) Changing one’s religion to other than Islam after having learned about Islam and understanding it. (Allah has said that “Whoever seeks other than Islam as a din, it will not be accepted from him”).
e) Claiming that Allah can become manifest in His creation (e.g., take the form of a man).
f) Believing in reincarnation.
g) Negating any one of His known attributes (e.g., the 41 attributes mentioned in Song 2 of the Guiding Helper). Included in this is claiming that the Universe was created by other than Him or that He was born from something else. Included in this also is claiming that the Universe had no beginning in time.
h) Claiming that one has sat alongside with Allah literally speaking or claiming that one has ascended to visit Him literally speaking.
i) Claiming that a person after the time of Prophet Muhammad ibn `Abdullah is a real prophet from Allah (and that Prophet Muhammad is not the last prophet). Included in this is claiming that one has received revelation from Allah (like a prophet)
k) Stating that it is possible that the prophets lied to us (or did not have the other qualities mentioned in Song 2 of the Guiding Helper).
l) Claiming that the message of Islam is only for Arabs (or only for another select group).
m) Claiming that one will enter Paradise (literally) while still in this world.
n) Claiming that the punishment and reward in the next life is *only* confined to being metaphorical.
o) Calling all of the Companions of the Prophet (all together) disbelievers.
p) Denying any of the necessarily known and obvious parts of the din (e.g., claiming that formal prayer, fasting in Ramadan, Zakat, and Hajj is not obligatory; or that the nineteen beliefs mentioned in Song 3 of the Guiding Helper are incorrect (but differences in detail are allowed))
q) Claiming that there is no need to worship Allah externally any more after becoming spiritually advanced. For example, claiming that the formal prayer is no longer wajib after one has reached some high spiritual station with Allah.
r) Denying any part of the Qur’an left by the Prophet (May Allah bless him and give him peace).
s) Intentionally adding to (inserting one’s own words into) or changing any part of the Qur’an left by the Prophet (May Allah bless him and give him peace) [Included in this is fabricating *obligatory* tenets of belief or *obligatory* acts of worship which have no basis in the primary texts].
t) Claiming that others besides Allah could produce the Qur’an.
u) Claiming that the later scholars (e.g., Imam Malik, Imam al-Shafi`i) were better than the prophets.
[QF: page 323: line(s) 7-18: {book 17, chapter 10: clarification}]
The way the scholars have reached these above list of 21 acts that make one “misguided” is by extensively studying the Qur’an (and Allah’s statements about guidance and misguidance in it) and also the actual interpretation of the Qur’an by the Prophet and the early Muslims.
Other acts not listed above do not have total support among the authentic scholars of our din as acts that make one become misguided and exit the sphere of Islam.
As a final note, the true scholar is very careful before calling people misguided or labeling them as kafirs as the Prophet (May Allah bless him and give him peace) has said:
When a man says to his brother [in din], O Disbeliever. This [word] comes back/over to [at least] one of them. If the mentioned person is as claimed, then it goes to him, else it comes back to the person who uttered the words.
[{Muslim, iman, bayan hal al-iman man qala li akhihi ya kafir, hadith #92}]
– Guidinghelper.com