Just as the word “crusade” may mean many things depending on the context in which it is used, so also does the Arabic word “Jihad” have many meanings depending on the context in which it is used. However, unlike “crusade”, the term or concept of “jihad” has never been understood by classical Muslim scholars to include or justify “Holy War” – fighting others purely due to religious differences, or forcing others at the point of the sword to accept Islam. So, while Muslims definitely conquered various lands for varying justifiable and unjustifiable reasons in history, there was never any organised attempt to force conquered people to convert to Islam, as evidenced by their current demographics and enduring places of worship in Muslim lands, and as recorded by even non-Muslim historians.
Suffice it here to quote Professor Emeritus Sir Thomas Arnold who writes:
“…of any organised attempt to force the acceptance of Islam on the non-Muslim population, or of any systematic persecution intended to stamp out the Christian religion, we hear nothing. Had the Caliphs chosen to adopt either course of action, they might have swept away Christianity as easily as Ferdinand and Isabelle drove Islam out of Spain; by the same method which Louis XIV followed to make Protestantism a creed whose followers were to be sentenced to death in France; or with the same ease of keeping the Jews away from England for a period of three hundred [and] fifty years. The Eastern Churches in Asia were entirely cut off from communion with the rest of Christendom throughout which no one would have been found to lift a finger on their behalf, as heretical communions. So that the very survival of these Churches to the present day is a strong proof of the generally tolerant attitude of the Mohammedan [sic] governments towards them.”
A simple study of the areas of consensus of classical Muslims scholars regarding when warfare or fighting others is permissible, who and what is a legitimate target, and the conduct of warfare in Islamic law, is sufficient to make clear the “Just War” concept behind the military form of jihad in Islam. It is also why unprovoked aggression against others, terrorism, and insurgency are actually regarded as punishable offences in Islamic Law.
Some Muslims have definitely tried to instrumentalise, misuse and abuse the concept of jihad for unislamic purposes. However, as is clear from a study of Islamic history, from the time of the Prophet (p) and his companions, the concept of jihad has never been a reason for undermining peaceful co-existence between Muslims and people of other faiths in multi-religious societies. On the contrary, the concept of jihad is at the core of a Muslim’s struggle for justice and against oppression of even non-Muslims and for the protection of their places of worship. It is at the heart of a Muslim’s commitment in the struggleagainst terrorism and in preventing all forms of extremism both in the past and into the future.
 Most nations at some time in their histories, have conquered, occupied or colonized others for various reasons.
 Hugh Goddard, Christians and Muslims: From Double Standards to Mutual Understanding, RouteldgeCurzon, London, 1995,pp.126-142; See also, K.S. Ramakrishna Rao, Islam and Modern Age, Hyderabad, 1978; James A. Michener, Islam: The Misunderstood Religion, Reader’s Digest (American edition), May 1955; Edward Gibbon, History of the Saracen Empire, London, 1870.
 Sir Thomas Arnold, The Preaching of Islam: A History of the Propagation of the Muslim Faith, Westminster A. Constable & Co., London, 1896, p.80
 See Ahmed Al-Dawoody, The Islamic Law of War: Justifications and Regulations, Palgrave Macmillan, New York, 2011, p.107-146, 147-196; Muhammad Naqib, Ishan Jan and Abdulrashid Lawan Haruna, International Humanitarian Law, IIUM Press, Gombak, Malaysia, 2015, pp.203-219; See also: Khaled Abou El-Fadl, Rebellion and Violence in Islamic Law, Cambridge University Press, Cambridge, 2006.