TAUNGGYI, Myanmar -- After a ritual prayer atoning for past sins, Ashin Wirathu, a Buddhist monk with a rock-star following in Myanmar, sat before an overflowing crowd of thousands of followers and launched into a rant against what he called the "enemy" -- the country's Muslim minority.
"You can be full of kindness and love, but you cannot sleep next to a mad dog," Mr. Wirathu said, referring to Muslims. "I call them troublemakers, because they are troublemakers," he told a reporter after his two-hour sermon. "I am proud to be called a radical Buddhist."
The world has grown accustomed to a gentle image of Buddhism defined by the self-effacing words of the Dalai Lama, the global popularity of Buddhist-inspired meditation and postcard-perfect scenes from Southeast Asia and beyond of crimson-robed, barefoot monks receiving alms from villagers at dawn.
But over the past year, images of rampaging Burmese Buddhists carrying swords and the vituperative sermons of monks such as Mr. Wirathu have underlined the rise of extreme Buddhism in Myanmar. Buddhist lynch mobs have killed more than 200 Muslims and forced more than 150,000 people, mostly Muslims, from their homes.
Mr. Wirathu denies any role in the riots. But critics say his anti-Muslim preaching is at the very least helping to inspire violence.
What began last year on the fringes of Burmese society has grown into a nationwide fundamentalist movement whose agenda now includes boycotts of Muslim-made goods. Its message is spreading through regular sermons across the country that draw thousands of people and through widely distributed DVDs of those talks. Buddhist monasteries associated with the movement are also opening community centers and a Sunday school program for 60,000 Buddhist children nationwide.
The hate-filled speeches and violence have endangered Myanmar's path to democracy, raising questions about the government's ability to keep the country's towns and cities safe and its willingness to crack down or prosecute Buddhists in a Buddhist-majority country.
The killings have also reverberated in Muslim nations across the region, tarnishing what was almost universally seen abroad as a remarkable and rare peaceful transition from military rule to democracy. In May, Indonesian authorities foiled what they said was a plot to bomb the Myanmar Embassy in Jakarta in retaliation for the assaults on Muslims.
Mr. Wirathu, the spiritual leader of the radical movement, skates a thin line between free speech and incitement, taking advantage of the new freedoms at a fragile time of transition. He was himself jailed for eight years by the now-defunct military junta for inciting hatred. Last year, as part of a release of hundreds of political prisoners, he was freed.
In his recent sermon, he described the reported massacre in March of schoolchildren and other Muslim inhabitants in the central city of Meiktila, documented by a human rights group, as a show of strength. "If we are weak," he said, "our land will become Muslim."
Buddhism would seem to have a secure place in Myanmar. Nine in 10 people are Buddhist, as are nearly all top leaders in the business world, government, military and police. Estimates of the Muslim minority range from 4 to 8 percent of Myanmar's roughly 55 million people, while the rest are mostly Christian or Hindu.
But Mr. Wirathu, who describes himself as a nationalist, says Buddhism is under siege by Muslims who are having more children than Buddhists and buying up Buddhist-owned land. In part, he is tapping into historical grievances that date to British colonial days when Indians, many of them Muslims, were brought into the country as civil servants and soldiers.
The muscular and nationalist messages he has spread have alarmed Buddhists in other countries. The Dalai Lama, after the riots in March, said killing in the name of religion was "unthinkable" and urged Myanmar's Buddhists to contemplate the face of the Buddha for guidance.
Ashin Sanda Wara, head of a monastic school in Yangon, says the nation's monks are divided nearly equally between moderates and extremists. He considers himself moderate. But as a measure of the deeply ingrained suspicions toward Muslims in the society, he said he was "afraid of Muslims because their population is increasing so rapidly."
Many in Myanmar speculate, without offering proof, that Mr. Wirathu is allied with hard-line Buddhist elements in the country who want to harness his movement's nationalism to rally support ahead of elections in 2015.