Is it Haram to backbite about non- Muslims?
Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
The ruling in this issue differs according to the condition of the Kafir (non-Muslim).
If this Kafir is a belligerent, then it is permitted to transgress his honor; however if he is a free non-Muslim under Muslim rule, then his honour is protected
Al- Shafii says in his book Asma Al Mattalib: "Backbiting a Kafir (non Muslim) is forbidden if he is free under Muslim rule, because if one does so, he makes him avoid paying Jizya and break the pact".
As the Prophet (Sallallahu Alaihi wa Sallam) said: "Whoever backbites and defames a free non-Muslim under Muslim rule will enter hell-fire." (Reported by Ibn Hibban in his Sahih). However, it is permissible to do so, if he is a belligerent, because the Prophet (Sallallahu Alaihi wa Sallam) used to order Hassan, may Allah be pleased with him, to say defamatory poetry on the Mushrikin (polytheists).
Imam Ahmed reported in his Musnad with an authentic chain of narration, the defamatory poems of Hassan, narrated by Al-Barra Bin Aazib, may Allah be pleased with him, said: "The Prophet (Sallallahu Alaihi wa Sallam) told Hassan Ibn Thabit "Say defamatory poems about the polytheists, the Ruh Al Qudus (Jibreel) is with you".
Allah knows best.
You can search for fatwa through many choices