That’s true for most of the Middle East, Turkey and North Africa.
Folks don’t realize that Islam didn’t come about until ~630 AD.
The dominant religion in most places where the Romans had any say became Christianity under Constantine in the early 4th century.
You have BS Hollywood movies rewriting history, such as “Kingdom of God,” intended to make the Muslims out as victims post 9-11. More Hollywood activism. Reality is, the Muslims invaded, enslaved, tortured, desecrated, raped, pillaged, destroyed churches/temples and force converted the people conquered on their march West.
The Crusades, now taught in US schools as a bad thing, were a REACTION to the Muslim invasions, not the other way around. Realize, Spain and even Italy were partially occupied by Muslims just a few years prior to the first Crusade. The term slav (as in the Slavic people) is where the word slave comes from, and these people lived in the East where the Muslims invaded repeatedly (Romania for example ~200 invasions). Constantinople is to the Eastern Orthodox as the Vatican is to Catholics, and all of Turkey (Byzantine Empire) is today Muslim.
Islam conquered by military might, out-bred, and usurped the rule in lands where they immigrated. This is even the case in more recent times, see Lebanon or Sudan as examples. They have been using the same MO for centuries, it’s part of their doctrine, many of their leaders speak very openly about this; it’s no secret. Only folks in the West today are blind to this because they are secular and project their values onto them (they cannot put their mind around a society organized around religion), are historically ignorant, not united as the Muslims are on this greater cause, and motivated by pure greed.
Islam is a threat. It is the only religion where the more devout/orthodox someone is, the greater a threat they pose. It is the ONLY religion like it. You can put Buddhists, Christians, Hindu, Zoroastrians, Bahia, Shinto, Jews in a room and they can figure out how to work together, but Muslims don’t mix with anyone. Yet in the West we use every possible opportunity to blame ourselves for their attacks, their doctrine, their history, their leaders, their laws... The idea that possibly that religion is fu#4ed up, automatically gets a label slapped on ones forehead: racist, xenophobic, Islamophobic.
You cannot have Islam and modern Western democratic, constitutional and free societies coexist. The Sharia clashes with every Western societies law since it defies the ideas of equal rights for women, LGBTQIA, other religions. Their ideas of dress, food, crime and punishment, free speech, freedom of movement, sexuality, freedom/expression of religion are all defined in their religion and are INCOMPATIBLE with Western society. Conflict is preprogrammed and the policy makers (folks like Obama, Merkel...) that are allowing mass immigration into Western societies are outright criminal in their behavior.
If you want to explain Islam to someone born and raised here, that went to a US public schools, gets nothing but MSM and social media, but is a bit older, explain it to them like this: Islam is no different than had the Waco branch divinians grown in numbers to 1.97 billion and controlled ~20% of the earth landmass. Both David Koresh and Mohamed were taking the Bible/Torah, interpreting it the way they wanted, and adding a lot to it which served them (i.e. Mohamed wanted a lot of women and some as young as 6, David Koresh liked little girls also). Imagine an illiterate, murdering, slave trading, polygamist, pedophile starts his own religion and carves out his empire through force and by conquering others, and then you understand Islam. Christianity albeit abused by the power hungry and greedy, is doctrinal about showing the other cheek, forgiveness, love your neighbor, you should be slow to anger, convert people with love and by telling them about the gospel, don’t judge (he without sin cast the first stone)... That is in contrast to the Koran and in particular chapter 9: https://qurancomplete.com/chapter-9/ Lying and breaking agreements is OK with an Infidel, if you have the upper hand force them into submission and convert them through force. Chapter 8: https://qurancomplete.com/chapter-8/ strike them at the neck (why you see so many decapitations), wage war with the nonbelievers, burn an apostate to death (why they burn those to death which convert away from Islam): https://www.youtube.com/watch?v=cfdasSFz1v0
In the West, a secular MSM tries to tell people that these are radicals, extremists, that Islam is the “religion of peace.” Sadly, this religion of peace phrase is no where to be found except first in a George W. Bush speech post 9-11. It’s all in how you frame things, but when polls (Pew a few years back) show that ~49,000,000 Pakistani’s and ~16,000,000 Muslims in Nigeria support ISIS (~20% of the population), you’re no longer talking about some fringe minority. Within the Islamic world, these ideas have a footing because they are doctrinal and with a historical precedent. The only people that are fools are those in government and the MSM that are essentially believing that who they are dealing with has the same value system as they do. That’s not the case. Bin Laden would have inherited billions, could have lived an opulent life of luxury and was college educated as a civil engineer. He had been dealing with the Russians and later us for many years (he knew what we can do). He knew very well that what he was doing with 9-11 amounted to signing his own death warrant while condemning himself to a life where he would be chased and living in austere/destitute conditions until killed. That’s not what motivates a Clinton, Obama, Biden, Schumer, Romney, McConnell, Cheney, Bush. The people here which talk about “religion of peace” (actually it means submission, which is very different than peace) are in reality using a sound nice phrase which is neither doctrinal based nor historically accurate, they are projecting their value system onto people where a good percentage does not think that way. They think everyone is like they are, an unprincipled slime ball that is for sale: motivated by pure greed for money and power.
So I read the quaran myself, as well as some of the hadiths. I was amazed at how violent Muhammad's teachings are. He repeated his violent teachings many times -- it's easy to get the point. You correctly stated that his followers invaded and desecrated and raped and killed everywhere they went. It turns out, that's exactly what Muhammad taught to do.
It's incredible that the Christians waited so long to begin the crusades. I'll never know why the Christians waited until so many Christian lands were violently taken over before mounting up an organized resistance.