Ayatollah Muhammad Hashimi Salihi
Islam has emphasised the unity of Muslims so much that maybe after associating things with God (polytheism) there is no subject [i.e. disunity] that it has forbidden more, to the extent that it has been said:
ﺑﻨﯽ اﻻﺳﻼم ﻋﻠﻰ دﻋﺎﻣﺘﲔ ﮐﻠﻤﺔ اﻟﺘﻮﺣﻴﺪ و وﺣﺪت اﻟﮑﻠﻤﺔ
Islam was built upon two pillars: the confession of the oneness of Allah, and unity in the profession to faith.
Therefore violating the lives, property or honour of Muslims is a major sin and is prohibited in the religion of Islam. Furthermore it makes it impermissible to disrespect the beliefs of any religion or sects among the Islamic schools of thought.
From another perspective, suicide attacks against Muslims and their mass killings in various countries are those things that have been divinely prohibited. These are instances of corruption on the earth and unpardonable sins that lead to an eternity in the fires of Hell. All Muslims, including Shi‘is and Sunnis, should be vigilant against the plots of the enemies of Islam, schismatic activities, and groups that do takfir.
The responsibility of all Muslims is to show the world the true face of Islam, the face of a religion of mercy, love and kindness and a social order based on the principle of ‘dispute with them in the best way’ (Qur’an 16:125). It is necessary that Muslims cooperate in protecting our brotherhood in the furtherance of Islam1.