What is the ruling on praying behind an imam who was subjected to sodomy in his childhood and youth, and with his consent, despite him being a memorizer of the Qur'an and having a beautiful voice?

If the Imam repents and mends his ways, there is no harm in him being an Imam, and prayers performed behind him are valid. However, if he persists in his wrongdoing, he must be advised. If he does not repent, efforts must be made to remove him and replace him with a righteous person, because a transgressor is not fit for imamate; people follow his example, and he could be a cause of their tribulation.

As for the validity of prayer behind a transgressor, the majority of scholars hold that it is valid, though disliked. Imam Al-Shafi'i explicitly stated that prayer behind a transgressor or an innovator is disliked but valid if performed. Sheikh al-Islam Ibn Taymiyyah mentioned that the Imams agreed on the dislike of praying behind a transgressor, and they differed on its validity, but they did not dispute that he should not be appointed.

If the Imam is a transgressor and does not heed advice, he must be removed if possible without causing discord. Otherwise, prayer should be performed behind someone else if possible, as a deterrent to him. If that is not possible, it is permissible to pray behind him to achieve the benefit of congregational prayer. And if there is a fear of discord from praying behind someone else, then one should pray behind him to avert the discord.