What is the ruling on praying the festival prayer behind an innovator imam?

Question:
The questioner says: We live in a city, and we pray the festival prayer behind a man from among the people of innovation. What is better: to pray behind him, or to pray separately? We are a large group.

Answer:
We do not know about this innovation; we do not know what type of innovation it is. I am afraid that you consider it an innovation when it is not an innovation. We do not know. So if it is confirmed that he is an innovator, do not pray behind him. But if it is just a suspicion, or if you judged it to be an innovation when it is not, there is no harm in the Muslims all praying together. The gathering of Muslims is required.
Unless you are certain that this imam is an innovator in an innovation that amounts to disbelief. Even an innovation that does not reach the level of disbelief does not prevent praying behind him. Especially in the festival prayer and the Friday prayer. It is required for Muslims to gather and pray together. Even if their imam has shortcomings or some sins, unless it reaches the level of disbelief.
If it reaches the level of disbelief, do not pray behind him, or if it is shirk (associating partners with Allah), do not pray behind him. But for anything less than disbelief and less than shirk, pray behind him, even if he is not fully committed, because the gathering is required. The gathering of Muslims is required, and their division is forbidden. Yes.