In my country, the phenomenon of cursing the religion is widespread, even among children. I also heard that a nearby mosque imam curses the religion, even though he leads people in prayer and delivers Friday sermons. I ask: Is it obligatory to ascertain that the imam does not curse the religion outside the mosque? Is it permissible to pray behind any imam about whom we know nothing, whether in a university, a mosque, or on the street? Is the quality of his Quran recitation and sermon sufficient to pray behind him?

All praise is due to Allah. The default assumption for those who ascribe to Islam is the validity of their Islam. The default assumption for imams is the validity of their prayers and the permissibility of praying behind them. Therefore, pray behind any Muslim whose prayer is valid without experiencing obsessive doubts or uncertainties. Do not refrain from praying behind imams unless you have absolute certainty that they have committed an objectionable act. If you know of someone who has done so, it is obligatory to advise them and explain that cursing the religion of Islam is apostasy and disbelief, by the consensus of scholars.