Migrants from pre-Englightenment societies almost always raise the general crime levels, take value that they didn't earn, and become the new underclass.
Look at Irish and Italian immigrants in the US in the 1800s. We came from countries that did not have the same level of education, without the history of liberal philosophy, and as a result we caused a lot of damage to the US -- between organized crime, debauchery, civil unrest, general violence, but also, politically/socially. We didn't understand the American political space, we voted for statist governments, and then began taking over the police forces and unions and mobilizing them against our rivals (blacks, Polish and Jews).
Eventually, we were assimilated, but that was much easier -- we were already Christians (albeit Catholic), and a lot of us could pass for a more desirable nationality. So far, Middle Eastern immigrants have shown little interest in assimilating at all.
Essentially xenophobia is the only reason why people are against immigration.
Do you realize that there are indigenous christians of all denominations in the ME or there's some kind of dominance hierarchy among denominations and churches of the world that I am not aware of?
But if we were talking casually about, say, Hong Kong, and I said the Hong Kong-ese speak Cantonese, would you complain because some percentage do not?
Or if I said Spanish people speak Spanish?
It's not a useful distinction to draw unless you provide it in the context of some larger argument.
My comment was on the state of the predominant Irish culture at the time of the diaspora.
By 1800 Ireland had been victim to hundreds of years of British misrule, shortly followed a major famine.
Our culture was devastated, our institutions were devastated, our life expectancy was in the mid 30's. We had little experience in self-governance, little experience of Democracy, Catholics were banned from most universities, couldn't fully own land until 1778.
It was even illegal for Catholics to teach elementary school, so childhood education was in an unimaginably desperate state.
Worst of all, Irish immigrants (unlike the H1Bs of today) mostly came from the lowest rungs of society in this already destitute nation and culture.
When my Irish great great grandmother came here she was 16, sent to America by her stepfather (along with her younger brother) because he no longer wanted to care for another man's children. She was fortunate enough to have come from a family of domestics for a wealthy estate, so she spoke well, and could cook and clean. She was comparatively lucky. Even so, it took multiple generations before my family pulled out of poverty, in NYC, and became a normal middle-class family.
Trying to assimilate a population like that into a nation with limited government and social institutions, as the US was in the 19th century, is a recipe for disaster. And it was, for a long time, a disaster.