Do Muslims believe violence is acceptable?

Answer 1

No, all true Muslims believe in peace for all humanity. Islam is the religion of peace. Eeven its greeting which is "Salam" is the Arabic Word for "peace". Violence in Islam is not acceptable even against animals.

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Answer 2

Yes, with conditions. Islam is not a pacifist religion like the Jains or Quakers. Just War and religiously sanctioned war (Jihad) are parts of Islamic Doctrine. Muslims commonly cite the precondition for just war and violence to be "oppression" or prohibition of Muslims to openly practice Islam. What counts as "oppression" depends on individual Muslims' interpretations. Some Muslims hold that images of Muhammad count as oppression, others do not. Some Muslims hold that the existence of Secular States in the Islamic World count as oppression, others do not. Some see political and economic corruption as oppression, others do not, etc.