Is it permissible for a Muslim to pray behind an ignorant or polytheistic imam known for his polytheism and hypocrisy? And is prayer valid behind an imam who curses the Divine Essence during marital disputes?

It is preferable that imams be the most knowledgeable and jurisprudent among those present, but the absence of a satisfactory imam is not considered an excuse for abandoning congregational prayer. The preponderant opinion is that if a person's prayer for himself is valid, then his imamate is also valid. Therefore, whoever finds only an impious or an innovator as an imam is not permitted to absent himself from the congregation, due to the Prophet's (peace be upon him) saying: "They pray for you; if they are right, it is for you, and if they are wrong, it is for you and against them." The Companions and the Successors prayed behind imams who were not satisfactory in their religiosity. However, prayer behind a proven disbeliever, against whom the evidence has been established, is not valid, due to the saying of Sheikh Ibn Baz: "Whoever prays behind someone who associates partners with Allah, his prayer is not valid."