"1. Terrorism is above all murder. Murder is strictly forbidden in the Qur’an. Qur’an 6:151 says, “and do not kill a soul that God has made sacrosanct, save lawfully.” (i.e. murder is forbidden but the death penalty imposed by the state for a crime is permitted). 5:53 says, “… whoso kills a soul, unless it be for murder or for wreaking corruption in the land, it shall be as if he had killed all mankind; and he who saves a life, it shall be as if he had given life to all mankind.”
2. If the motive for terrorism is religious, it is impermissible in Islamic law. It is forbidden to attempt to impose Islam on other people. The Qur’an says, “There is no compulsion in religion. The right way has become distinct from error.” (-The Cow, 2:256). Note that this verse was revealed in Medina in 622 AD or after and was never abrogated by any other verse of the Quran. Islam’s holy book forbids coercing people into adopting any religion. They have to willingly choose it.
3. Islamic law forbids aggressive warfare. The Quran says, “But if the enemies incline towards peace, do you also incline towards peace. And trust in God! For He is the one who hears and knows all things.” (8:61) The Quran chapter “The Cow,” 2:190, says, “Fight in the way of God against those who fight against you, but begin not hostilities. Lo! God loveth not aggressors.”
4. In the Islamic law of war, not just any civil engineer can declare or launch a war. It is the prerogative of the duly constituted leader of the Muslim community that engages in the war. Nowadays that would be the president or prime minister of the state, as advised by the mufti or national jurisconsult.
5. The killing of innocent non-combatants is forbidden. According to Sunni tradition, ‘Abu Bakr al-Siddiq, the first Caliph, gave these instructions to his armies: “I instruct you in ten matters: Do not kill women, children, the old, or the infirm; do not cut down fruit-bearing trees; do not destroy any town . . . ” (Malik’s Muwatta’, “Kitab al-Jihad.”)"