What is the ruling on the imamate of an imam who swears by other than Allah, while knowing the impermissibility of that, and what should we do concerning him if we advise him and he does not respond?

The prohibition of swearing by other than Allah is a serious matter, and a severe warning has been issued concerning it. Whoever swears by other than Allah has committed shirk (polytheism) or kufr (disbelief). Some scholars have deemed swearing by other than Allah to be haram (forbidden). If one believes in the object sworn by with reverence akin to the reverence due to Allah, then he has disbelieved. If the swearer does not hold such a belief, then he does not disbelieve, but he becomes a fasiq (transgressor). Prayer behind him is valid, although it is preferable for someone else to lead. He must be advised, and if he does not respond, his matter should be brought to the attention of the ruler. As for him not having a strong personality, this does not affect the validity of praying behind him.