Question: Among the Masjids (mosques) built by religious organizations are some belonging to Muslim sects like those who call for the arbitration or exercise of human reason in judging the Prophetic Ahaadeeth and hence deny thousands of authentic Hadeeths. Or sects that divert the Names of Allaah and His Attributes from their original meaning. They circulate the wicked phrase: “The Salaf (Predecessors) are Ahkaam (more precise and nearest to the truth) and the Khalaf (Successors) are more knowledgeable.” They also promulgate among the public a phrase that states, “Allaah is there, everywhere.” Is it permissible to offer Salaah (prayer) in one of these Masjids behind an Imaam (the one who leads congregational Prayer) from these sects?
What if the Imaam of one of these Masjids recants this, should I demand from him to declare himself no longer affiliated to such sects or his saying so is deemed sufficient?
Answer: Those who deny the sound Ahaadeeth authentically reported from the Prophet (peace be upon him) and reject their meanings, are wrongful sinners; but declaring them to be disbelievers, is a matter of detail… read more here.