Fitna is a word in the Arabic language which, I believe has no equivalent in English only if 'Fitna' itself will enter English.
One meaning to it is temptation or appeal, but it's not that which I'm worried about it is the other meaning, maybe you can prove me wrong in averring to that there is no equivalent:
although some sources refer to it as sedition and civil strife, I don't think that is 100% accurate. Arabic Scholars (and there are not plenty considering that the bulk of Arab world speak dialectal Arabic according to their region/country) concur to that. As difficult as it is to explain, 'Fitna' is as I cited earlier is more than intricate to elucidate because a civil strife is not Fitna, it is part of the phenomena of Fitna. If one would elaborate the tale of Imam Ali and the reasons behind his death and that of his male offspring, maybe then and just then one would have a somewhat better understanding of the word. I understand the word but I cannot explain it patently and I struggle to explain it in my mother tongue due to its complexity.
To give you an element of hint: it is a jumble of fragmentation, chaos, unrest, scandal, disorder, mistrust, hatred, grudge and could include mass killings (between dissidents/family members/or other people (with no relation).. but dissidents and relatives is more common).
Reasons to Fitna: Religion, but not necessarily. فتنة (in Arabic)