Teenagers streamed past applauding peers to the arena stage -- to show their openness to a possible priestly or religious vocation. At another point, youth stood to acknowledge that they had proclaimed Jesus as Lord of their lives for the first time that weekend. Others extended their hands to pray over them.

When a leader said, "Let's celebrate Mass," the young people cheered and applauded. They did the same when reminded that they have Jesus in the Eucharist and when introduced to the main celebrant and homilist: Cardinal Seán O'Malley.

It was the Steubenville East youth conference, held last July 13-15 at UMass Lowell with an estimated 2,500 participants.

This was one of 25 youth conferences that Franciscan University of Steubenville in Ohio is holding across North America this summer, according to the website steubenvilleconferences.com. Life Teen hosts some of them, including this one. Altogether, more than 50,000 teenagers were expected to participate.

This year's theme was "Revealed," from 1 John 4:9: "In this way the love of God was revealed to us: God sent his only Son into the world so that we might have life through him."

"God's love is deeper and His plan for our lives is greater than anything the world has to offer -- will we allow Him to reveal it to us?" asks the website.

"Jesus' Plan A for your life is that you become a saint," Father John Parks said at Sunday's Mass. A conference speaker and vicar for Evangelization for the Diocese of Phoenix, he added, "We all have a secondary vocation" for living out Plan A.

Marriage is so important, a reminder that love is real and lasting, he said. A family with four children has changed the course of history four times.

He had married people stand and be recognized while the crowd applauded and cheered.

"A saint is only going to be attracted to another saint," Father Parks said, encouraging chastity.

Marriage points to Christ's love, a sign no longer needed in heaven, he said. But priests and religious live the reality of heaven now.

"A stop sign says, 'Stop,'" Father Parks said. "Celibacy says, 'Go to Heaven.'"

He invited young men to come forward if they were open to the possibility of God calling them to be priests. They were not making a commitment, he said.

Teenagers streamed to the stage as the audience cheered and applauded, then rose in a standing ovation.

"I invite you to get to know a priest of your diocese," Father Parks said. "Also, I'd encourage you to attend a vocations retreat" and reach out to the vocations director.

Next, women religious were invited to stand. Young women considering such a vocation were invited to come forward. Many did so, wrapping their arms around each other.

"I couldn't believe how many kids went up," said Tina Anderson, a first-time attendee and chaperon from St. Joseph Parish in Charlton. "My son was one of them. ... I just started to cry -- he's serious." She said the 17-year-old had talked about priesthood, but this made it concrete for her, and is such a blessing for the family, though he has not made any commitment to this vocation at this time.

"It was so heart-warming to see so many young people truly open their heart to Jesus," she said.

"It was beautiful to see so many sisters and so many priests giving up so much of their time for young people...Just the love and attention they showed these kids at the drop of a hat. And to see the kids from different groups...getting each other's contact information, accepting each other as one big family."

"It got, like, deep," said Ivan Polanco, a 15-year-old from Holy Family of Nazareth Parish in Leominster. "During confession, I got a lot off my chest. During adoration it got really emotional for me. ... I met a lot of people -- Connecticut, Canada, Rhode Island."

He said this year's conference seemed better; last year's didn't feel as intimate with God and other people.

"It was a really good experience -- I feel how he was here with me," said Florencia Guerra, 14, a first-timer from Holy Family.

"I never really experienced Church this way," said Natalie Boutiette, a 15-year-old from St. Joseph's in Charlton. "It was engaging. ... When I get home, I can feel more connected with my church."

Henry Fredette, 14, another first-timer from St. Joseph's, called the conference amazing.

Jackie Tran, a chaperon from Our Lady of Vilna Parish in Worcester, said they brought nine young people.

"They love it, especially the music," she said. "They always thought that the Mass is boring, the music is boring. ... They say they like the Mass now."

She said they loved the talks, and especially cherished a repeated point: "We are born originals, but many of us die photocopies." She said that reminded them to live in the unique way God calls them to.

Cardinal O'Malley said he was happy that many priests and deacons could join them for Mass.

Cardinal O'Malley talked about the "heroes" of rugged individualism in Western movies being replaced by those who are "celebrities just because they're famous."

He told about a doctor telling a woman that, for her husband to survive, she'd have to care for him and let him control the remote control. When he asked what the doctor said, she replied, "You're going to die."

"We are placed on this earth to take care of one another" -- or the patient will die -- Cardinal O'Malley said. "Our task is...to repair the world. Our world needs a lot of care. Lone rangers and celebrities won't cut it."

He spoke of the gods of money and self-advancement, but said faith brings fulfillment and added, "I urge you to be part of a community of faith."

The cardinal talked about a letter in a Holocaust museum. The writer said he saw children poisoned by educated physicians, and other horrors perpetrated by those with schooling, so he was suspicious of education.

Cardinal O'Malley talked about advancements, from automobiles to space exploration, but also 20th-century violence, including Apartheid and legalized abortion.

"Our faith is a light that helps us to see deeper into reality," he said. "We discover...what we have to do with our lives. ... We have received a light that we need to share with others."