What is the ruling on praying behind an imam who collects donations for building a Tijani zawiya, knowing what this order contains of polytheistic matters, and is he considered an apostate by his action, such that prayer behind him is not permissible?

The Tijaniyya sect is among the sects of innovation and misguidance. Assisting innovators in building their Zawiyas, where they practice manifestations of shirk (polytheism) and bid'ah (innovation), is impermissible. It is not permissible for an Imam to obey the Ministry in collecting donations for building a Zawiya for this sect, because "there is no obedience to a creature in disobedience to the Creator." However, merely assisting in building places where polytheism is practiced with Allah is not disbelief, unless it leads the doer to be pleased with disbelief and polytheism. The majority of jurists have mentioned the prohibition of a Muslim's work in building churches, but they did not deem it disbelief. The one who assists is not ruled to be a disbeliever if he falls into an act of disbelief, except after the establishment of proof against him. Therefore, what the Imam did by collecting donations for building the Tijaniyya Zawiya is forbidden but not disbelief, and praying behind him is permissible and valid.