The claim
"Islam was primarily spread through military conquest and forced conversion."
The short answer
Historical evidence shows that Islam spread primarily through trade, scholarship, and the personal example of Muslims. Many of the largest Muslim populations today, such as Indonesia and Malaysia, were never conquered by Muslim armies.
Evidence-Based Clarification
The Quran Prohibits Forced Conversion
The Quran explicitly and repeatedly prohibits compulsion in religion. This is not a minor verse — it is a foundational principle that Muslim scholars across all schools of thought have upheld for 1,400 years. The Prophet ﷺ himself lived alongside Jewish and Christian communities in Madinah under the Constitution of Madinah, which guaranteed religious freedom.
Historical Context
Indonesia, the largest Muslim country in the world, and Malaysia were never conquered by Muslim armies; Islam reached them through merchants, scholars, and teachers whose conduct attracted people to the faith. Where Muslim armies did conquer, conversion was slow: Bengal was conquered around 1204, yet its mass conversion came centuries later as settlers cleared and farmed the eastern delta. In Iran and Egypt a Muslim majority took centuries to form, and large non-Muslim communities remain to this day — evidence that forced conversion was not practised systematically.
PRIMARY SOURCES (5)
"There shall be no compulsion in religion. The right course has become distinct from the wrong."
لَا إِكْرَاهَ فِي الدِّينِ ۖ قَد تَّبَيَّنَ الرُّشْدُ مِنَ الْغَيِّ
— Surah Al-Baqarah 2:256check the original
"And say, 'The truth is from your Lord, so whoever wills — let him believe; and whoever wills — let him disbelieve.'"
وَقُلِ الْحَقُّ مِن رَّبِّكُمْ ۖ فَمَن شَاءَ فَلْيُؤْمِن وَمَن شَاءَ فَلْيَكْفُرْ
— Surah Al-Kahf 18:29check the original
"Invite to the way of your Lord with wisdom and good instruction, and argue with them in a way that is best."
ادْعُ إِلَىٰ سَبِيلِ رَبِّكَ بِالْحِكْمَةِ وَالْمَوْعِظَةِ الْحَسَنَةِ ۖ وَجَادِلْهُم بِالَّتِي هِيَ أَحْسَنُ
— Surah An-Nahl 16:125check the original
"Bengal came under Muslim rule from 1204, but mass conversion followed centuries later, as the agrarian frontier moved into the eastern delta and its cultivators gradually adopted Islam."
— Richard M. Eaton, The Rise of Islam and the Bengal Frontier, 1204–1760 (University of California Press, 1993)
"Estimates of conversion in Iran, Iraq, Syria, Egypt and Spain show Muslim majorities forming gradually, over several centuries after the conquests."
— Richard W. Bulliet, Conversion to Islam in the Medieval Period: An Essay in Quantitative History (Harvard University Press, 1979)