Environmentalists have long promoted Earth Day with activities from park cleanups to street marches. But next Saturday, they’ll add a new tool to their strategy list — a “big sing.”

St. Mark’s Episcopal Cathedral in Minneapolis will open its doors to Earth Day volunteers with an event called Create Harmony, featuring the Rev. John Bell of Scotland, known as the Pete Seeger of progressive Christian songfests. The widely known minister leads “group sings” across the globe, often incorporating folk music from less-developed lands.

Standing in a church, singing boldly with friend and stranger isn’t the usual route to creating a green economy. But group sings increasingly are being used to build community and common purpose. Plus it can be just plain fun, said Steve Schewe, a cantor at St. John’s Episcopal Church in Minneapolis who helped spearhead the event.

“A group sing is a way for people to embody their values,” said Schewe. “You don’t have to be an opera star. It lets people embody their hope for their community — in this case for a clean environment.”

In fact, the event is one of two major community sings that will be echoing in church halls next weekend. The other, at Plymouth Congregational Church in Minneapolis on April 22, is unrelated to Earth Day and activism, instead featuring renowned English classical choral composer John Rutter.

These group singalongs are having a revival of sorts in the United States, in particular with various community and social justice themes, said Philip Brunelle, a choral scholar and artistic director of the VocalEssence choral ensemble. They were hugely popular, often held under big tents, during the Christian revivalist movement of the 1800s, he said.

“It has expanded, and it’s not just religious anymore,” said Brunelle. “Singing in a group enhances a sense of purpose and creates a sensitivity to those around you. It doesn’t matter what you’re singing — hymns, folk songs. Just to get hundreds of people together, singing, is thrilling.”

The event at St. Mark’s shows how these songfests embrace both their history and a future. Bell, for example, is a veteran charismatic minister who is expected to mix social justice and spiritual themes as he directs the crowd in harmony and verse.

But the event also includes Twin Cities younger talent such as the Tiyumba African Drum and Dance Company, 11-year-old hip-hop artist Priest Jones, teen poet Lulu Priede and young adult poet Pierre Fulford. The Rev. Dee Jackson McIntosh of Lighthouse Covenant Church will emcee the event.

“Most social justice movements have been accompanied by communal song,” said the Rev. Craig Lemming of St. John’s Episcopal Church. “This is just another reiteration of that.”

Bell has long said that singing is a powerful tool to internalize beliefs.

“What we sing shapes what we believe,” he said. “In the Christian church, for example, look at what we’ve been singing about traditionally — plenty about the beauty of the world, but nothing about God’s mandate to conserve it. Today, people of diverse faiths are joining together to care for the Earth and call for justice.”

Sponsors at the April 21 environmental singalong include St. Mark’s Cathedral, St. John’s Episcopal and Minnesota Interfaith Power & Light. It’s part of a day of Earth Day activism that starts with a cleanup of Loring Park in the morning and ends with networking at a Climate Justice Happy Hour at a local brewery.

St. Mark’s Cathedral, across from Loring Park, is looking forward to the many voices filling its sanctuary.

“The spirituality of singing reminds us that none of us is an island,” said the Rev. Paul Lebens-Englund of St. Mark’s. “When we [group] sing, we’re doing something together that we could not do apart.”

“Reverend Bell has done extraordinary work around the world bringing people together to sing about the things they care about,” said Claire Curran of Minnesota Interfaith Power & Light. “We are so pleased to have him lead us in a big sing on Earth Day — a day that we all can agree is a sacred day to honor and heal our planet.”