Is it permissible to pray behind a mosque imam who writes amulets and talismans and refuses all forms of dialogue regarding them, knowing that he is an elderly man with a heart condition, and there is a fear that a health crisis might occur to him as a result of such a discussion?

The writing of amulets from the Quran and supplications is a matter of scholarly disagreement, and the preponderant opinion is that it is forbidden. However, wearing them does not constitute disbelief (kufr), nor does it render the one who does so a profligate (fasiq). As for amulets not derived from the Quran, they are forbidden, and they become polytheism (shirk) if one believes that they inherently cause benefit or harm. Praying behind an imam who does something that is a matter of scholarly disagreement or something forbidden is permissible and valid, as long as he has not committed an act of disbelief.