Those who know nothing of Islam pretend that Islam counsels against war. Those are witless. Islam says: Kill all the unbelievers just as they would kill you all! Does this mean that Muslims should sit back until they are devoured by [the unbelievers]? Islam says: Kill them, put them to the sword and scatter [their armies]. ...Islam says: Whatever good there is exists thanks to the sword and the shadow of the sword! People cannot be made obedient except with the sword! The sword is the key to paradise, which can be opened only for holy warriors!
Ayatollah Ruhollah Khomeini: Islam Is Not a Religion of Pacifists (1942)