Story highlights Pussy Riot sang an anti-Putin song in Moscow's Christ Savior Cathedral

Three band members face charges of hooliganism and up to seven years in prison

They pleaded not guilty and apologized to offended Christians, RIA-Novosti says

Amnesty International says the trial "never should have taken place"

Three members of the Russian punk rock band Pussy Riot pleaded not guilty Monday to charges of hooliganism after performing a song criticizing President Vladimir Putin in a Moscow church, Russia's state news agency reported.

The charge, which carries a potential seven-year sentence, stems from an unusual performance they gave in February.

"Mother Mary please drive Putin away," the band screamed, their faces covered in neon masks, inside Moscow's Christ Savior Cathedral.

The anonymous, feminist protest band called it a punk prayer.

Three of the women were arrested soon after, and have been in custody ever since. Two of the women have young children.

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On Monday, band members apologized to Orthodox Christian believers if they felt they had been insulted, state news agency RIA-Novosti reported.

Nadezhda Tolokonnikova, 23, Maria Alyokhina, 24, and Yekaterina Samutsevich, 29, grinned at cameras as police brought them from a van into the court, waving their handcuffed arms behind their backs.

They appeared in court in an enclosure that forced them to bend down to speak through small window to be heard.

Amnesty International said Monday the trial "never should have taken place."

John Dalhuisen of Amnesty said the singers had been making "a legitimate protest -- this is not a criminal offense. They must be released immediately."

"They dared to attack the two pillars of modern Russian establishment -- the Kremlin and the Orthodox Church. While many may have found their act offensive, the sentence of up to seven years in prison they may expect on the charges of hooliganism is wildly out of all proportion," he said.

Pussy Riot member Tolokonnikova is bearing up well in jail, her husband, Peter Verzilov, told CNN earlier this month.

"She looks very good and she's taking it as she's supposed to take it -- as very political and very artistic; as a very solid, creative and powerful person," he said, based on fleeting glimpses of her in court.

Pussy Riot specializes in sudden, often illegal public performances, including one in Moscow's Red Square.

"We did realize that at some point, (they) could get arrested. That was always a possibility, but of course no one expected the arrest would come after this particular performance," Verzilov said.

The punk prayer was inspired by the women's anger about the relationship between the Russian government and the Orthodox Church.

The Orthodox leader Patriarch Kyril has been widely reported as saying Putin's years in power have been a miracle from God.

But the band's behavior in one of Russia's most sacred cathedrals has outraged many of the country's faithful.

"This is a disgusting thing to do," one woman told CNN.

"They should go to jail," said another. "A year or two. Let them to think about their behavior."

But even some of those who were offended believe the women should not be in jail.

"If necessary, God will punish them," said one man. "It must be not be cruel punishment."

The women also have passionate supporters who say they are victims of political persecution.

Verzilov says he has told his 4-year-old daughter who's to blame.

"Gerra knows that Putin has put Nadia in prison and he's not letting her out. We have to find a way to defeat him to free Nadia," he said.

The Russian president hasn't commented on the case.

Pussy Riot is only one small part of the recent anti-Putin protest movement.

But the decision to jail and prosecute these women has ensured that the band's colorful face masks have become one of the opposition's most powerful symbols.