I am not a teacher.
Please, check if the following passage is grammatically correct. Thanks
The society of country A and its sectarian structure are fundamentally different from those of country B.
There may be a problem. The antecedents of the pronoun "those" includes "sectarian structure". I suspect that you mean instead that the structure of country B is not sectarian. If so, this requires a bit of a rewrite to fix, maybe something like, "The society of country A is fundamentally different from that of country B, as is its structure---sectarian rather than ???." Also, I'm not sure what a country's "structure" is, but maybe that becomes clearer as you go on.
Nearly forty percent of the inhabitants of country A affiliate with minorities.
I find "affiliate" to be so delicate that it is not clear. I pictured them hanging out with minorities. Maybe, "Nearly forty percent of the inhabitants of country A belong to minority groups."
All these minorities are afraid of destabilizing the country which could result in a civil war, or rather, a bloody sectarian war.
Comma after "country".
In case such a war breaks out, the minorities' people will be those who will pay its price.
"If" such a war breaks out. "Pay the price" is idiomatic; "its" makes the reader stumble.
Therefore, all these elements are interested in maintaining the stability even if it means accepting the repressive regime of Mr. X.
Watch your pronouns (like "these"). It is easy to rely too much on them. Repetition makes things clearer, often at the expense of style, but not always, and maybe not if you do it right. If there was more to this passage, and other "elements" have been discussed earlier, then "these" works. If not, try, "all groups within the country are interested ...."
Also, "stability" is a mass noun here: "maintaining stability".
To sum up, the danger of destabilizing the regime in country B could result in bandit gangs terrorizing the streets, whereas instability in country A could lead to a sectarian bloodshed.
The danger can't result in anything (an error of sense), and "bloodshed" is a mass noun. Maybe, "To sum up, destabilizing the regime in country B could result in bandit gangs terrorizing the streets, whereas instability in country A could lead to sectarian bloodshed."
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