The crackdown is much broader than the action taken last week against two prominent Mormons, who were threatened with excommunication: Kate Kelly, the founder of the Ordain Women movement, and John P. Dehlin, creator of the Mormon Stories podcast and an advocate for gay Mormons.

It has affected Mormons perceived as dissidents from across the ideological spectrum: liberals such as Ms. Kelly, Mr. Dehlin and others who support same-sex marriage, and conservatives who devoutly believe Mormon teaching and Scripture but criticize the church as straying from it, such as Mr. Waterman and Denver Snuffer, a lawyer in Utah who blogs and writes books about Mormonism. Mr. Snuffer said on his blog that he was excommunicated for apostasy last fall.

Image Kevin Kloosterman

“This is clearly boundary maintenance,” said Jan Shipps, a professor emerita of history and religious studies at Indiana University-Purdue University Indianapolis, who has written extensively about the Mormon Church. “They had essentially created a porous boundary, but once you have a porous boundary, sooner or later you’re going to have to maintain a boundary that says, ‘This is as far as you can go.’ ”

Mormons are such active bloggers and voluble writers that they have created a whole universe of sites, which they call the Bloggernacle, where they go to discuss their faith. The church cannot police them all or shut them down, but it can demonstrate to members where it draws the boundaries of acceptability by scaring those who stray.

The church, in a statement this week, said that disciplinary actions were handled by local leaders and were not coordinated or directed by church headquarters. But some of the Mormons facing disciplinary actions said they had been told by their bishops that the instruction to investigate Internet activity came relatively recently from more senior leaders.

“It feels scary to have all the words I say on Facebook and Twitter monitored,” said Kevin Kloosterman, a mental health therapist in Sycamore, Ill.