𝗜𝗦𝗟𝗔𝗠𝗜𝗖 𝗘𝗫𝗣𝗔𝗡𝗦𝗜𝗢𝗡𝗜𝗦𝗠
Is Islam an Expansionist Religion? What does that mean....
This is a very interesting question and one that is habitually brought up in an attempt to condemn Muslims for their history of military conquest and dominance.
But it is really a bad thing for Muslims to have exerted their dominance and power to establish, preserve and expand the realms of Islam over several centuries?
The Quran informs us that World Domination is not the objective nor can everyone become a Muslim, had Allah wanted that to be the case - he could have done so without any difficulty, to think that everyone MUST become a Muslim is literally equated to ignorance.
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"And if Allah had so decided, He would indeed have gathered them to the guidance. So definitely do not be one of the ignorant"
Surah an-Aaam (6), Ayah 35
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Islam itself does not aim to conquer the entire world and force everyone to embrace the faith, this is a gross exaggeration and misappropriation of its message. However, Muslims - like any other civilization - will strive to expand their reach and impose their culture, sciences and worldview above that of competing civilizations, there is simply nothing to apologize about in this regards, you either conquer or become the conquered, there was (and is) no middle ground.

Nature has a way of filling voids and eliminating vestiges.Nations who become stagnant become subject to the ambitions of those that are not, the entire history of mankind is a practical demonstration of this undeniable fact.
How exactly did the other great world empires and civilizations including the Greeks, Egyptians, Persians, Romans, Assyrians - attain the status and historic regard that they greatly enjoy today? Did they all create vast empires through non-violent means, could the Muslims have resisted the Mongol Hordes if it were not for the military might and ingenuity of the Mamluks? or are Muslim Empires the only ones expected to attain their objectives by pure non-violent means?
There are many presuppositions that are deeply embedded in such questions, among them are the following
1. Muslims should never have sought to expand their influence beyond Arabia
2. Muslim Empires had somehow innovated a new convention that was not already practiced without any reservation by the Romans, Persians, Assyrians and other world powers at the time
3. Islam would have been perfectly well placed to remain benign and non-violent, there was no need to be expansionist (supposedly because the peace loving Romans and Persians would never have sought to encroach on the Muslims, at any point)
4. Expansionism is Always inherently evil and is Never a good thing (you can probably see the problem with this statement just by looking at the current leading nations and their foreign polices) There are clearly obvious contradictions and disingenuous sentiments with all of the above-mentioned "concerns", not least when we consider how the most dominant world cultures and civilizations established their empires and continue to preserve their dominant stance globally, because the military industrial complex is certainly not going out of fashion anytime soon.
The question of Muslim expansionism needs to be revisited and revised without the need to apologise or in some cases - fabricate - stories to appease the insatiable appetite of critics who jump from argument to argument at a whim. History has its conventions, one of them is that if you do not conquer then you are probably one of the conquered, there simply was not place for a prominent civilisation that was unwilling or (more importantly) incapable of defending its interests and position.
Ibn Khaldun, in his famous Muqaddima makes the point of explaining how empires and dynasties go through a cyclical process of being established by fierce and lesser-civilized tribes (or the "barbarians at the gate" in European terms) who encroach on the more refined and cultured city-dwelling nations who were supposedly weakened by their metropolitan lifestyles and sensibilities (first world privileges such as who can use masculine or feminine pronouns).
The newly seated barbarian+conquerors then get accustomed to the fine luxuries and resources acquired from the conquered peoples, over time the old guard becomes the new bourgeoisie (for want of a better term) who is then subject to the attack and conquests of less civilized and more brutal tribes coming from the Bedouin/Barbarian environment, thus the cycle perpetuates itself.
A great example of this would be the Muslims of Andalus who were compelled to seek the help of the desert-dwelling battle-hardened Murabittun coming out of Africa and into the luxurious exploits of the Andalusian realms, eventually - the latter replaced the former, it was in fact inevitable. (If you can't defend your treasure, is it really yours anymore?)