Burma’s parliament is now beginning to sort through numerous proposals for constitutional change, while President Thein Sein’s government sporadically engages the country’s minorities on reforms to end more than six decades of ethnic violence. But no major Burmese political leader—not even Suu Kyi herself—has confronted the most explosive threat to the transition: religious intolerance.

The problem is evident in the case of the besieged Muslim Rohingya minority, which mainly lives in Arakan (Rakhine) state in the west, bordering Bangladesh. The Rohingya (who are generally not recognized as citizens of Myanmar) have born the brunt of violence that has killed an estimated 300 Muslims and displaced a quarter of a million during this transitional period. Like another stateless people, the Roma of Europe, they have long been held back by poverty, crime, discrimination, and dismissal as interlopers. Just in the last few days, the United Nations received credible reports of a massacre of dozens of Rohingya Muslims by a Buddhist mob.

But these issues extend beyond the rather isolated Arakan state. A broader campaign of Buddhist religious bigotry has gained momentum, inflamed by the “969 campaign” of extremist monks and lay followers. The most visible leader of the movement is the Mandalay-based monk Ashin Wirathu, who a decade ago was convicted and jailed (and later released) for inciting religious violence. He has compared Burma’s Muslim minority (an estimated 5 percent of the population) to “mad dogs” and “African carp” who “breed quickly” and are “very violent.” He is believed to receive financing and encouragement from shadowy conservative forces who see religious chauvinism as perhaps the only way to counter the electoral appeal of Suu Kyi’s National League for Democracy.

It is not only Muslims who are targeted. Religious freedom is broadly imperiled. Christians from the Chin and Kachin minorities have long been subjected to threats, intimidation, and discrimination, including the burning of churches. Allegedly perpetrated by local officials, these acts are (at least) tolerated by a national government that effectively treats Buddhism as a state religion. Militant monks are now pressing for legislation that would severely restrict the right of Buddhists to marry outside the faith.

Everything we know about mass ethnic killing urges us to take hateful language, discriminatory laws, and sporadic violence very seriously. They are not only in themselves human rights violations; they constitute early warning signs of a potential calamity. Any religious sentiment—with its strong sense of the holy and profane, and its clear identification of members and outsiders—is vulnerable to cynical exploitation. Buddhism is not immune to this; just ask Sri Lanka’s Muslim and Christian minorities.