What is the ruling on offering the funeral prayer behind an imam who curses religion?

Cursing the religion of Muslims is disbelief, and whoever curses the religion of Islam is a disbeliever, whether serious or joking, even if he claims to be a believer. This is because Allah said: "and have approved for you Islam as religion" [Al-Ma'idah: 3], and He said: "And whoever desires a religion other than Islam, it will never be accepted from him" [Al Imran: 85], and He said: "Indeed, the religion in the sight of Allah is Islam" [Al Imran: 19]. So, whoever curses this religion, whether seriously or jokingly, has committed an act of disbelief that expels him from the fold of Islam, and he must repent to Allah. If there is clear evidence that someone curses the religion, it is not permissible to pray behind him, neither the funeral prayer nor any other, until he repents.