Praise be to Allah.

Firstly:

We must be extremely cautious about describing any Muslim as a disbeliever, for one of the gravest of sins is for a Muslim to describe his Muslim brother as a disbeliever when he is innocent of that.

It was narrated by Ibn Hibbaan (81), al-Bukhaari in at-Taareekh al-Kabeer (2907), and al-Bazzaar (2793) that Hudhayfah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “What I fear most for you is a man who recites the Qur’an until, when the its beauty begins to appear on him and he becomes a defender of Islam, he then drifts away from the path for as long as Allah wills, then he discards it and throws it behind his back, and he goes to his neighbour with sword in hand, and accuses him of shirk.” I said: O Prophet of Allah, which of them is more deserving of being accused of shirk, the accused or the one accuser? He said: “The accuser.”

Ibn Katheer (may Allah have mercy on him) said:

Its isnaad is jayyid.

End quote. It was classed as hasan by al-Albaani in as-Saheehah (3201).

A similar idea is referred to in the report narrated by al-Bukhaari (6104) and Muslim (60) from Ibn ‘Umar (may Allah be pleased with him), who said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “Any man who says to his brother, ‘O disbeliever,’ it will apply to one of them. Either it is as he said, otherwise it will come back to him.”

See the answer to question no. 33769.

Secondly:

This stern warning only applies in the case of one who accuses a Muslim of being a disbeliever when he is innocent of that, and he has the audacity to accuse him of that without any proof. However, if the one who is accused of shirk deserves that accusation, then there is no blame on the accuser, because he is describing him as he deserves to be described. Hence the Prophet (blessings and peace of Allah be upon him) said: “Any man who says to his brother, ‘O disbeliever [kaafir],’ it will apply to one of them. Either it is as he said, otherwise it will come back to him”, meaning if the one who is accused of being a disbeliever has actually done something to deserve to be described as such, then there is no blame on the one who says to him, O disbeliever.

Shaykh Ibn Baaz (may Allah have mercy on him) said:

“Any man who says to his brother, ‘O disbeliever [kaafir],’ it will apply to one of them” means: if he does not deserve that. That applies if he says to him, O disbeliever, when he does not deserve that. However, if he does deserve that, then this description is befitting to him.

End quote from Fataawa Noor ‘ala ad-Darb (6/253).

The apparent meaning of the hadith is that it is applicable to the Khawaarij, who were the first people to describe Muslims as disbelievers. They described as disbelievers those who commit major sins and those who commit ordinary sins, and they fought against them with the sword whilst leaving the idolaters alone, and they fought the Muslims. This is how they are usually described in hadiths and reports other than this one.

Thirdly:

It is not permissible to describe a Muslim as a disbeliever unless proof is established against him that what he does constitutes disbelief.

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said:

If proof did not reach him, then he is not to be deemed a disbeliever, because Allah, may He be exalted, says (interpretation of the meaning):

“And this Qur'an was revealed to me that I may warn you thereby and whomever it reaches”

[al-An‘aam 6:19]

“And never would your Lord have destroyed the cities until He had sent to their mother a messenger reciting to them Our verses. And We would not destroy the cities except while their people were wrongdoers”
[al-Qasas 28:59]

“Indeed, We have revealed to you, [O Muhammad], as We revealed to Noah and the prophets after him…

[We sent] messengers as bringers of good tidings and warners so that mankind will have no argument against Allah after the messengers. And ever is Allah Exalted in Might and Wise”

[an-Nisa’ 4:163-165]

“And never would We punish until We sent a messenger”

[al-Isra’ 17:15].

Ibn ‘Uthaymeen also said:

It cannot be said to a specific person, O disbeliever, unless proof is established against him and it becomes clear to him that what he is doing constitutes disbelief.

End quote from Fataawa Noor ‘ala ad-Darb (4/2).

See also the answer to question no. 111362.

In the answer to question no. 85102 we stated that before ruling that a Muslim is a disbeliever or an evildoer, two issues must be examined:

1. There should be evidence from the Qur’an or Sunnah that the view or action in question actually constitutes disbelief or evildoing.
2. This ruling is applicable to one who has a particular view or does a particular action, if the conditions for describing him as a disbeliever or an evildoer are met in his case, and there are no impediments to that ruling.

The most important conditions are as follows:

1. That he is aware of his infraction that led to him being described as a disbeliever or an evildoer.
2. One of the impediments to that ruling is if he said or did something that constitutes disbelief or evildoing without intending to do so.
3. Another impediment to that ruling is if he was following a plausible misinterpretation, meaning that he has some specious argument on which he based his view, thinking that it is true evidence, or he is not able to understand the shar‘i evidence correctly.

Fourthly:

It is very important, with regard to this issue, to understand that even though a specific person may be excused because of mistakes or ignorance, or because of some plausible misinterpretation, and the like, that does not mean that the action itself cannot be described as disbelief or shirk. Rather this description is established for particular actions on the basis of Allah’s ruling concerning them. This is the most important point that we are trying to make, and the most important idea to note in this regard, especially at times of ignorance when people drift away from the light of Islam, and at times when the Muslims are weak and oppressed, when Muslims have no power or authority, and in many cases examining such situations has become a theoretical issue with no practical implication. What matters most is calling people to Allah regardless of time and place, to explain how a particular action is against the teachings of Islam and passing judgement as dictated by Islamic teachings, so as to warn the doer against doing it.