More than 25,000 evangelical Christian youth landed Friday in San Francisco for a two-day rally at AT&T Park against "the virtue terrorism" of popular culture, and they were greeted by an official city condemnation and a clutch of protesters who said their event amounted to a "fascist mega-pep rally."

"Battle Cry for a Generation" is led by a 44-year-old Concord native, Ron Luce, who wants "God's instruction book" to guide young people away from the corrupting influence of popular culture.

Luce, whose Teen Mania organization is based in Texas, kicked off a three-city "reverse rebellion" tour Friday night intended to counter a popular culture that he says glamorizes violence and sex. The $55 advance tickets for two days of musical performances and speeches were sold out, but walk-up admission was available for $199.

After stops in Detroit and Philadelphia in the next few weeks, Luce wants to unleash a "blitz" of youth pastors into the communities to do everything from work with the homeless to find new ways to bring others to Christ. He challenged youth leaders to double the size of their groups in the next year.

And then he plans to return to San Francisco next year to chart their progress.

That's bad news to Assemblyman Mark Leno, D-San Francisco, who told counter protesters at City Hall on Friday that while such fundamentalists may be small in number, "they're loud, they're obnoxious, they're disgusting, and they should get out of San Francisco."

Luce didn't flinch in the face of the counter protest. The author, host of the "Acquire e the Fire TV" cable television program and a President Bush appointee to a federal anti-drug-abuse commission, wants teens to find Bible-based solutions for the spread of sexually transmitted disease, teen pregnancy, drug abuse and suicide.

The villains, Luce said, range from the promiscuity and "sexualization" of young people on MTV and the popular online meeting hub MySpace.com to a corporate culture that spends millions trying to woo the under-21 crowd.

Battle Cry will try to bring them back to God through two days of religious rockers, speakers and the debut of what Luce called a Christian alternative to My Space.com.

"This is more than a spiritual war," Luce said. "It's a culture war."

Military metaphors abound in Luce's descriptions of the struggle. He tells young people of how "an enemy has launched a brutal attack on them." At a pre-Battle Cry rally Friday afternoon on the steps of City Hall, Luce told his mostly teenage audience that "terrorists of a different kind" -- advertisers -- were targeting them and that they were "caught in the middle of the battle."

"Are you ready to go to battle for your generation?" he asked, and the young people roared "yes!" and some waved triangular red flags flown from long, medieval-looking poles.

Luce's approach has been praised by conservative leaders from the Rev. Jerry Falwell to Fox News commentator Sean Hannity. Much of the statistical backing for the horrors Luce sees on TV is provided by the Parents Television Council, which is funded by conservative foundations such as the Lynde and Harry Bradley Foundation.

Those alliances weren't lost on the 50 protesters representing a rainbow of San Francisco's left -- from abortion-rights advocates to anti-war activists to atheists -- who staged Friday's counter protest.

"There is a real intolerancy to homosexuality in a lot of these organizations," said Peter Cobb, an organizer with Not In Our Name.

Earlier this week, the Board of Supervisors passed a resolution condemning the "act of provocation" by what it termed an "anti-gay," "anti-choice" organization that aimed to "negatively influence the politics of America's most tolerant and progressive city."

Luce said it was the first time one of his events has been officially condemned.

A Battle Cry invitation to teenagers made plain the symbolism of gathering in San Francisco for a pre-event rally at "the very City Hall steps where several months ago, gay marriages were celebrated for all the world to see."

Same-sex marriage "is another sign of the end of times," said Sherilyn David, referring to the apocalypse that some fundamentalist Christians believe is foretold in Scripture. The 22-year-old San Jose administrative assistant came to Battle Cry with 15 other young Christians on Friday and will be joined by 60 other friends Saturday.

Christian Gallion, a 15-year-old in town with his Assembly of God youth group from Humboldt County, shrugged off being called "fascists" by counter demonstrators.

"It doesn't bother me," Gallion said. "It's a beautiful city, and we don't have anything against the protesters."

His youth pastor had no interest in engaging in political debates.

"I'm not here to hate anybody," Scott Thompson said. "This isn't about Bush or gays or anything other than being here to worship together."

That's not how some liberal leaders saw it.

"Even if it is done by a Barnum & Bailey crowd with a tent and some snake oil, I think we need to pay attention to it," said Supervisor Tom Ammiano, who authored the condemnation resolution. "We should not fall asleep at the wheel."

Separated by barricades and six feet of neutral sidewalk in front of City Hall, the two sides traded amplified calls to arms Friday.

On one side of the barricade was girl carrying a sign that said, "Instead of porn, show us Godly relationships." On the other, a woman held one that said, "I moved here to get away from people like you."

As Battle Cry organizers walked through the crowd of young people telling them, "Don't engage with them," one rain-soaked counter demonstrator yelled, "And next time, come back in summer."

Luce said they will.

"We're going to be back here in a year, to see what kind of progress we've made," he said. "And we're going to be at AT&T Park. Or whatever it is called then."

E-mail Joe Garofoli at jgarofoli@sfchronicle.com.