This study is the first to simultaneously investigate country-level and platform-related context factors of toxic outrage, that is, destructive incivility, in online discussions. It compares user comments on the public role of religion and secularism from 2015/16 in four democracies (Australia, United States, Germany, Switzerland) and four discussion arenas on three platforms (News websites, Facebook, Twitter). A novel automated content analysis ( N = 1,236,551) combines LIWC dictionaries with machine learning. The level of toxic outrage is higher in majoritarian than in consensus-oriented democracies and in arenas that afford plural, issue-driven rather than like-minded, preference-driven debates. Yet, toxic outrage is lower in forums that tend to separate public and private conversations than in those that collapse varying contexts. This suggests that user-generated discussions flourish in environments that incentivize actors to strive for compromise, put relevant issues center stage and make room for public debate at a relative distance from purely social conversation.