A hanar religious sect and political advocacy group on the road to becoming a dedicated terrorist network.
The Acrimonious Tide formed in the wake of the Reaper War on outlying colonies of the Illuminated Primacy, within communities which had more than the usual contact with aliens, but weren't involved with them in the manner of the traders, business people or scientists; and thus had no reason to learn tolerance for alien ways. The group has become increasingly renegade as the Primacy becomes wary of their political platform and willingness to condemn aliens directly, and in increasingly impolitic ways.
In particular, the Acrimonious Tide directs hostility to the Asari Republics and the Systems Alliance, both of which are believed to have grievously offended the Enkindlers due to mishandling of preserved Prothean sites - the asari by maintaining their veil of secrecy over the Athame Beacon, the humans for failing to realize the wonders buried at Mars and Eden Prime.
Of late, the group has become willing to inflict violence on aliens, including assassinations, and has qualified as a terrorist organization.