Is it permissible to support a mosque controlled by Bid'ah (innovators) of the Maturidi school, knowing that it is the only mosque in the town?

The Ash'aris and Maturidis are the closest theological schools to the People of the Sunnah and Hadith. They are the People of the Sunnah in countries where the People of the Sunnah and Hadith are not present. There is no harm in cooperating with those in charge of the mosque, whether Ash'ari or Maturidi, in righteousness and piety, supporting charitable projects, and advising them gently and kindly on matters of disagreement.