Praise be to Allah.

It is not permissible to expel a Muslim from the houses of Allaah, even if he is an innovator, because they are houses that are built to establish the remembrance and worship of Allaah. The innovator is to be appreciated for his worship and will be rewarded for all the good that he does for the sake of Allaah, but he incurs sin for his innovation. So it is not permissible for anyone to prevent him from worshipping and obeying Allaah, rather we should help him in that and encourage him to attend the congregational prayers of the Muslims, in the hope that he may learn the Sunnah from the people of knowledge, and give up innovated matters of religion. 

The Prophet (peace and blessings of Allaah be upon him) even gave permission to some of the mushrikeen to enter the mosque, as in the story of Thumaamah ibn Athaal (may Allaah be pleased with him), when the Prophet (peace and blessings of Allaah be upon him) ordered that he be tied to one of the pillars of the mosque. That was before he became Muslim, and he became Muslim on the third day. He said to the Prophet (peace and blessings of Allaah be upon him): “I bear witness that there is no god except Allaah and I bear witness that Muhammad is His slave and Messenger. O Muhammad, by Allaah, there was no face on earth that was more hateful to me than your face, but now your face has become the dearest of all faces to me. By Allaah, there was no religion on earth that was more hateful to me than your religion, but now your religion has become the dearest of all religions to me. By Allaah, there was no city on earth that was more hateful to me than your city, but now your city has become the dearest of all cities to me” Narrated by al-Bukhaari (462) and Muslim (1764).   

Look at how his staying in the mosque became a cause of his being guided to Islam. How about the Muslims who take care of the maintenance of the mosque, give the adhaan, deliver the khutbah and so on, as mentioned in the question? 

When Ka’b ibn Maalik stayed behind from the campaign to Tabook, the Prophet (peace and blessings of Allaah be upon him) ordered that he be shunned and forbade the people to talk to him, and he even ordered him to stay away from his wife, but he did not forbid him to attend the prayers in congregation with the Muslims. 

He (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) forbade the Muslims to speak to us three among those who had stayed behind. So the people shunned us, or their attitude towards us changed, until it seemed to me that the land itself had turned hostile towards me and was no longer the land that I knew. We stayed like that for fifty days. As for my two companions, they stayed in their houses weeping, but I was the youngest and strongest of them. I would go out and attend the prayer, and go around in the marketplaces, and no one would speak to me. I would go to the Messenger of Allaah (S) and greet him with salaam, when he was sitting with the people after prayer, and I would say to myself: Did his lips move in response or not? Then I would pray close to him, stealing glances at him. When I focused on my prayer, he would look at me, then when I looked at him he would turn away.  Narrated by al-Bukhaari (2757) and Muslim (2769). 

When the Khawaarij manifested their bid’ah (innovation) and separated from the main body of the Muslims because of the idea and innovations they introduced, none of the Sahaabah ordered that they be removed or expelled from the mosques, because they are houses which Allaah has given permission to be built and His name mentioned in them. So it is not right for anyone to forbid that for which Allaah has given permission. 

‘Ali ibn Abi Taalib said concerning the Khawaarij: “They have three rights over us: that we should not initiate fighting with them so long as they do not fight us; that we should not prevent them from entering the mosques of Allaah to mention His name therein; and that we should not deny the booty to them so long as they have fought alongside us.”

Narrated by Ibn Abi Shaybah in al-Musannaf (7/562) with a hasan isnaad. 

What is prescribed in your case is to treat them kindly in the house of Allaah, and to strive to explain the Sunnah to them by all means. If you can prevent them from establishing their bid’ah, after asking the scholars and making sure that this particular action is indeed bid’ah, then you may prevent them from doing this bid’ah only, but you cannot prevent them from entering the mosque altogether. That is subject to the condition that preventing this bid’ah will not lead to trouble among the Muslims or to an evil that is greater than the bid’ah that you want to prevent. 

Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) said: 

Based on this, if the person or group combines good with evil in such a way that they cannot be separated, rather they will do it all or abandon it all, then it is not permissible merely to enjoin good or forbid evil, rather you should look and see. If the good is more prevalent, then it should be enjoined, even if that will entail a lesser amount of evil, and you should not forbid an evil if that means that a greater amount of good will be lost. In that case, forbidding evil would be more akin to blocking the path of Allaah and striving to stop people from obeying Him and His Messenger, and to stop people doing good. But if the evil is more prevalent then it should be forbidden, even if that means that a lesser amount of good will be lost. In that case, enjoining that good which entails a greater amount of evil is in fact enjoining evil and striving to disobey Allaah and His Messenger. If the good and evil are equal, then you should neither enjoin nor forbid, rather in some cases it will be better to enjoin (the good) and in some cases it will be better to forbid (the evil), and in some cases neither enjoining good nor forbidding evil will be appropriate, because the good and evil are so strongly connected. 

That has to do with specific issues. But when speaking about specific actions, then good should be enjoined in general and evil should be forbidden in general. 

With regard to a single person or group, then its good should be enjoined and its evil should be forbidden; its praiseworthy actions should be commended and its blameworthy actions should be criticized, in such a way that enjoining good will not cause most of the good to be lost or a greater evil to occur, and in such a way that forbidding evil will not cause a greater evil to occur or a greater good to be lost. If the matter is unclear then the believer should wait until the truth is clear to him, so that he will not do an act of obedience without the proper knowledge and intentions. 

End quote from Majmoo’ al-Fataawa (28/129-130); al-Istiqaamah (2/217-218). 

Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allaah have mercy on him) was asked: 

We have Shi’ah with us at work. Is it permissible for us to return their salaams? We also see them in the mosque praying on pieces of paper; is it permissible to expel them from the mosque? 

He replied: 

I say: treat them as they treat you. If they greet you with salaam, then return their salaams. It is not good to expel them from the mosque, rather some of them may be from among the common folk who do not know anything and have been misled by their scholars. If you are clever and call them in ways that are better, you may be able to influence them. Using violence is not something that is narrated in sharee’ah. Allaah loves kindness in all things. Now if you oppose them and say “Do not prostrate on pieces of paper, do not prostrate on stones” and the like, if the matter may be settled there and they will give up these things, that is good. But (the problem is that) they will persist, and the enmity and hostility between you will increase. What I think you must do is advise them first, especially the ordinary people. Advising does not mean attacking their madhhab and false religion. No, advising means explaining the truth to them and teaching them the Sunnah. Then after that, if you explain the Sunnah to them, I am absolutely certain that if they have real faith, they will come back to the Sunnah and give up their falsehood. If that happens, then that is better. If it does not happen, then you should treat them as they treat you. As for expelling them from the mosque, you have no right to do that. 

Liqaa’aat al-Baab il-Maftooh (no. 80, question no. 4). 

Finally: 

We should point out to you that not everyone who does an act of bid’ah (innovation) is an innovator, and not everything that you regard as bid’ah is necessarily an innovation. It is not permissible to take as a reference point in this issue the junior seekers of knowledge or those who are zealous about the Sunnah. They themselves need guidance, care and advice. For example, they may think that clasping the hands to the chest after rukoo’ (bowing) is a bid’ah. Do they judge the one who does that as an innovator? Do they want to expel such people from the mosques? Do they know that those who do that – clasping the hands to the chest after bowing – are among our imams and scholars? 

We appreciate these brothers for their enthusiasm for the Sunnah, but we do not want them to let their enthusiasm make them pass judgement on people or expel them from the houses of Allaah. How much we have suffered from categorization of people; do we want to bring that categorization into the houses of Allaah? We hope that this will not happen and we hope that they will be sensible and ask – as they have done in this case. Here the fatwa of the scholars is clear even with regard to extreme innovators such as the Shi’ah, and we should not neglect to call them and encourage them to follow the Sunnah in the way that is best. 

And Allaah knows best.