Others said the Catholics were part of an international plot orchestrated from the Vatican.

Sri Lanka’s dynamics bear striking similarities. During its civil war, fought against separatists from the Tamil minority, Sinhalese felt outnumbered because of the large Tamil community in nearby India. This gave many Sinhalese a sense of siege, deepening us-versus-them divides that have outlasted the fighting.

More recently, Sinhalese Buddhists have seen Sri Lanka’s Muslim minority as vanguards of a global Muslim horde. Last year, Sinhalese fears that Muslims were seeking to outbreed and replace them culminated in riots.

Conspiracies about foreign influence or minority birthrates are often driven by fears of a much more real change: a loss of status. Modern democracy demands that minorities be granted equal rights and opportunities, which can feel like a threat to majorities’ traditional hold on power.

Fears of existential, sectarian conflict can be self-realizing.

In 1960s Northern Ireland, Catholic civil rights marches, modeled on those of the United States, felt to some Protestants like part of a wider Catholic plot to overrun them.

Hard-line Protestants, acting in what they saw as self-defense, whipped up violent counter-protests, culminating in riots on both sides. In response, more Catholics joined violent republican factions, seemingly validating Protestants’ worst fears. The tit-for-tat cycle continued for decades.

Long after the peace process, and with Catholics and Protestants now near evenly numbered, a shared perception of being the aggrieved, vulnerable minority persists. So does the cycle of violence.