Question

Is expiation required of one who reviles a Muslim, such as saying to a Muslim “May the religion of your mother be cursed” [an Arabic form of insulting or cursing]?

Praise be to Allah.
    
    Reviling the faith or the religion or Islam is major kufr (disbelief), 
    according to scholarly consensus. The one who does this should be asked to 
    repent. If he repents, all well and good, otherwise he should be executed, 
    Allah forbid. See questions no. 
    
    
    42505 and
    
    65551. 

    
    With regard to reviling the religion of a particular Muslim person, such as 
    saying “May your religion be cursed” or “May the religion of your mother be 
    cursed” – if his mother is a Muslim – is also reviling the religion, as 
    appears to be the case, which is kufr as stated above. Some of the scholars 
    suggested that it may be interpreted differently, and that what is referred 
    to is the person and his religious commitment. This may be based on 
    circumstantial evidence. In this case he should be punished and disciplined. 
    In any case he should be asked to repent and the matter should be discussed 
    with him. 

    
    It says in al-Mawsoo’ah al-Fiqhiyyah: The fuqaha (jusrists) are unanimously 
    agreed that the one who reviles Islam or the religion of the Muslims is a 
    kafir (disbeliever). As for the one who reviles the religion of a Muslim, 
    the Hanafis said, as mentioned in Jami’ al-Fusooleen: The one who reviles 
    the religion of a Muslim should be denounced as a kafir, but his insult may 
    be understood as referring to that person’s bad attitude and bad treatment 
    of others, not Islam itself [because the word ‘deen’ in the phrase under 
    discussion may refer to one’s religion or to one’s way and conduct], in 
    which case he should not be denounced as a kafir. End quote. 

    
    Al-Shaykh ‘Ulaysh al-Maliki said: In it [in al-Barzali] there is another 
    issue, which is if a man ridicules the prayer and people who pray, and many 
    people testify against him, some of whom are credible witnesses and some are 
    not. If it is interpreted as ridiculing the worshippers because he thinks 
    ill of them, then it is to be regarded as reviling the Muslims, so he should 
    be disciplined as the judge sees fit. If it is interpreted as ridiculing the 
    worship itself, the correct view is that this is apostasy, because he has 
    done this openly and many people knew about it, which is different than 
    heresy, and the ruling on apostasy should be applied. End quote. 

    I 
    say: From this ruling it may be understood that the one who reviles Islam or 
    the religion or a madhhab (school of thought) is that this is often done by 
    some of the dregs of the common folk, such as donkey-drivers, camel-drivers 
    and servants, or it may be done by others. If he was referring to the 
    sharee’ah (religious laws) and the rulings that Allah has prescribed for His 
    slaves on the lips of His Prophet (peace and blessings of Allah be upon 
    him), then he is definitely a kafir. If he does this openly then he is an 
    apostate who should be asked to repent; if he repents, all well and good, 
    otherwise he should be executed. If he does not do it openly then he is a 
    heretic who is to be executed even if he repents. 

    
    If he was referring to an individual person and his religious commitment, 
    then this is reviling a Muslim and he should be disciplined as the judge 
    sees fit. The two cases may be differentiated on the basis of confession and 
    circumstantial evidence. Some scholars said that the ruling is the same in 
    the second case as in the first. In al-Badr it is narrated that Bahram said 
    concerning apostasy: If the one who does not pray says to the one who tells 
    him to pray: When you enter Paradise, lock the door behind you – if what he 
    meant is that prayer has no effect on one’s religious commitment then he has 
    apostatized, according to scholarly consensus, but if he meant that the 
    prayer of the speaker has no effect because it does not stop him from 
    committing immoral and evil actions, then there are two views as to whether 
    he is an apostate. End quote.  

    
    It is well known that the Holy Quran is also part of the religion, and 
    reviling it is kufr, as was stated by al-Barzali in several places. End 
    quote from Fath al-‘Aliy al-Malik fi’l-Fatwa ‘ala Madhhab al-Imam Malik.

    
    The other possibility that he mentioned may occur rarely, but the basic 
    principle is that cursing a person’s religion is cursing Islam, and no one 
    would do that but a reckless person who is so audacious that he transgresses 
    the sacred limits of Allah and commits this grave evil that may lead to his 
    doom. Because the other possibility is unlikely to be the case when someone 
    utters these words, al-Shaykh ‘Ulaysh (may Allah have mercy on him) did not 
    mention it anywhere else, when he was asked: What do you say about a man who 
    curses the religion of another, and a man who curses his madhhab, or one who 
    says to him, “May Allah curse your madhhab, the madhhab of cats” – are they 
    apostates? 

    I 
    replied: Praise be to Allah and blessings and peace be upon our master 
    Muhammad the Messenger of Allah (peace and blessings of Allah be upon him). 
    Yes, they are apostates because of saying this, and they deserve to be 
    executed if they do not repent, according to scholarly consensus, because 
    reviling religion or a madhhab is only done by the one who is a kafir, and 
    because it is worse than belittling it which implies kufr, and because it 
    comes under the second category mentioned by Ibn ‘Abd al-Salam, al-Qarafi, 
    Ibn Rushd and others. And Allah, may He be glorified and exalted, knows 
    best, and may Allah send blessings and peace upon our Prophet Muhammad. End 
    quote from Fath al-‘Aliy al-Malik.

    
    Secondly: 

    
    The expiation for reviling – whether one reviled the religion or the person 
    – is sincere repentance. If a person repents, Allah will accept his 
    repentance. Otherwise the one who reviled another deserves to be punished 
    and disciplined. Al-Nawawi (may Allah have mercy on him) was asked: What 
    should be done to the one who calls a Muslim a dog or a pig and other bad 
    words. Is he sinning? 

    
    He replied: Praise be to Allah. He is sinning and he should be punished, and 
    he has to repent. And Allah knows best. End quote from Fatawa al-Nawawi. 

    
    See also question no. 
    
    
    42505 for more information on the repentance of one who reviles the 
    religion. 

    
    And Allah knows best.