What is the ruling on insulting and reviling those who claim lineage to the noble Household of the Prophet (Ahl al-Bayt) after discovering their adoption of grave-worshipping Sufism and their commission of polytheistic acts, and is this considered an insult to the Messenger of Allah (peace be upon him)?

It is forbidden to curse Muslims, whether they are alive or dead, based on the Prophet's (peace be upon him) saying: "Cursing a Muslim is an act of wickedness, and fighting him is disbelief," and his saying: "Do not curse the dead, for they have already gone to what they have sent forth." Scholars have interpreted this prohibition as general, except for what is specifically excluded by evidence, such as criticizing narrators (for scholarly purposes). As for cursing disbelievers, it is prohibited if it harms a living Muslim, but it is permissible if there is a benefit in it, such as establishing justice. A Muslim is not given to cursing or slandering. Rather, he should adorn himself with good character and debate opponents with evidence and good counsel.