In court on Friday, lawyers for the victims argued that the Feb. 21 performance had unleashed a wave of extremism that culminated in a terrorist attack on two Muslim leaders in Tatarstan on Thursday, defense lawyers said.

The government picked a ripe opportunity to crack down, since many Russians found the cathedral performance offensive. It took months for the case to provoke support for the women, even in the opposition-minded city of Moscow. But the balance seemed to shift last month, when a roster of famous artists and musicians, including some vocal supporters of Mr. Putin, signed a petition contending that the case “compromises the Russian judicial system and undermines trust in the authorities.”

A poll released on Friday by the independent Levada Center found that a substantial proportion of Muscovites, 37 percent, took a positive view of the prosecution, and 50 percent had a negative view.

“When it began to turn into this fantastic biblical story, social attitudes toward the girls changed radically,” said Marat Guelman, a former political consultant and gallery owner whose projects have been denounced by religious activists.

“Most of the population now are not so much talking about what Pussy Riot did as much as their fear that these people who want to introduce some kind of Orthodox Taliban to Russia, that they will take power,” Mr. Guelman said. “So now I think the authorities are making a big mistake, taking revenge in this way. Society will not support this.”

Whether he is right will become clear only gradually, as state-controlled television reports on the prosecution of the three women, two of them mothers of small children. So far, the case has aroused intense interest only on the extremes of the political spectrum, a fact reflected on Friday outside the courthouse, where protesters wearing white ribbons tried to shout down Orthodox activists carrying Bibles.

“We are seeing an attempt to return the country not to the Soviet period, but to the 17th century,” said Lev Rubinstein, a poet who spent much of the morning there.