What is the ruling on praying in mosques where religious innovations are prevalent? And what is the ruling on praying behind an innovator?

Al-Halabi : He saysThe questioner : What is the ruling on praying in mosques where religious innovations are prevalent, and consequently, what is the ruling on praying behind an innovator imam?

The Shaykh : This is also a question that is very common these days. While it is a sign of good from one perspective, it is a sign of evil from another. It is a sign of good that, praise be to Allah, those who are eager to follow the Sunnah are increasing day by day, and that they are becoming aware of the many religious innovations in the mosques, among the imams and the mu'adhdhins, and the like. Therefore, they may feel hesitant about praying in these mosques filled with religious innovations, and about following these imams who contradict the Sunnah in much of their prayers. This is good. But until when will we continue with such questions, when we always and forever repeat two things:
The first thing is regarding following an innovator imam. We have inherited from generation to generation that it is a recommended practice to pray behind the righteous and the wicked. This is a belief mentioned in the creed of the people of the Sunnah and the community: praying behind every righteous person and every wicked person. This is in contrast to the Shi'ah, because the Shi'ah do not consider prayer valid except behind an infallible imam. I do not mean except behind the Shi'ah; no, the matter is more misguided with them. It is only behind an infallible imam, and this infallible imam, naturally, in their view, is only from the Shi'ah, from the People of the House. So the Salaf established for us this rule that we should pray even behind the wicked. Why?
Because it came in many hadiths that inform us that praying behind unjust and oppressive imams is permissible. Among this is his saying (peace and blessings be upon him), as in Sahih Muslim: And in the other hadith, which is more important, more comprehensive, and greater, he said about the imams: So what does it matter to a person whether he prays behind an innovator, whether he prays according to the Sunnah or contradicts it? If he hits the mark, it is for us and for him; and if he errs, it is upon him and for us. So in any case, we are gainers, like a saw that cuts both on the upstroke and the downstroke. If we pray behind a Sunni imam, it is for us; and if we pray behind an innovator imam, it is for us. But his innovation is upon him, and none of its sin reaches us. We repeat this always and forever regarding following these imams...
This is also a matter we have repeated many times, and we have mentioned that what is required of every Muslim is to practically avoid praying in decorated mosques that are filled with religious innovations. But the Messenger of Allah (peace and blessings be upon him) spoke the truth when he said: Today, it is rare to find a mosque that does not have a religious innovation or some of the decorations by which they claim to draw near to Allah (Blessed and Exalted is He). If there were mosques of both types, we would say: do not pray in these mosques that have these decorations and these religious innovations. It is established from Ibn 'Umar (may Allah be pleased with him) that he entered a mosque to pray the midday prayer, and he was surprised to find a person calling out and shouting after the adhan, saying: "Prayer, prayer!" So he said to his companion: "Let us leave this mosque, for there is a religious innovation in it." If we wanted to do what Ibn 'Umar did, we would have to stay in our houses, stay in our apartments; because there is hardly a mosque that does not have some decorations. These carpets are enough, and the images in them; sometimes there are forbidden images; either the image is forbidden, like a horse or the like, a lion, or it is crosses or the like. So there is hardly a mosque that does not have something that distracts. But, alas, some evil is less than some. If the matter is between praying alone in our houses and praying in decorated mosques led by innovator imams, then at that time we repel the greater evil with the lesser evil. Especially since this greater evil is not something we are obligated to do or that comes from us, but rather it comes from others. If we delay the congregational prayer, we have sinned and contradicted the saying of our Lord: Because He said this phrase after He said: There is no repetition here. He said: "And establish prayer and bow down with those who bow down." This is an observation that must not be forgotten. "And establish prayer and bow down with those who bow down." What is the point? That is, perform it fully That is, with the congregation of the Muslims. So if we leave the congregational prayer in these mosques, and we are not responsible for the decorations in them, or for the poor performance of prayer by some of the imams, we are not responsible for that poor performance or that; but we would be responsible if we prayed in our houses for contradicting the saying of our Lord: Yes.