The ruling on praying behind a person who holds to a religious innovation (bid'ah)

Question:
This questioner says: Abu 'Ali, peace be upon you, and Allah's mercy and blessings. What is the ruling on praying behind a person who holds to a bid'ah (religious innovation) and opposes the Sunnah?

Answer:
The bid'ah (religious innovation) varies. If it is a bid'ah that entails disbelief (kufr), then it is not permissible to pray behind him. If it is a major bid'ah from the major sins but does not reach the level of kufr (disbelief), this is considered open sinfulness (fisq), and it is not permissible to pray behind him either, according to the majority of scholars. As for if the bid'ah is minor and does not reach the level of a major sin, then the prayer behind its holder is valid, and if he finds a better imam, he should pray behind him. Yes.