"That's our call to the altar: what will you sacrifice?"
The Sunday morning event, dubbed Consumption Sabbath, is part sincere Christian worship, part performance art, all in the framework of an old-fashioned tent revival service.
In addition to Brother Aiden, the morning includes testimonies from environmental activists, gospel music and an altar call.
"Our souls are wounded and we are people of longing," Enns says of the call to Christians to convert to a less consumptive lifestyle.
"We welcome counsellors to help us with our pledge to be better and to do better."
Although the format is playful, right down to the red-and-white circus tent that can shelter about 100 people, the message of the day is quite serious, says one of the event's planners.
"We believe that the Earth belongs to God and is to be cared for and the resources of the Earth are for all humanity to be shared equitably and used in a sustainable way," says Esther Epp-Tiessen of Charleswood Mennonite Church.
"We feel that the church should be at the forefront of the movement of living sustainably and we know that's not necessarily the case."
For months, Epp-Tiessen and other members of her adult Sunday school class pondered how to combine activism with their congregation's focus on environmentalism. The group decided to plan a public event for Earth Day and invited people from other churches and denominations to participate.
At least two Winnipeg churches — Hope Mennonite and Grain of Wheat — have cancelled their Sunday services so their members can attend the Consumption Sabbath.
Admitting they might be poking a bit of fun at evangelical Christian tent meetings of the past, the theme to change sinful ways is still relevant, says Epp-Tiessen, 56, who recalls attending a revival meeting as a child.
"As I understand it, those tent meetings called to people to recognize their sins, to repent and to invite them to a transformed life," she says.
"We're inviting people to recognize how we're part of the problem with our addiction to fossil fuels and to invite them to a new way."
The several hundred participants expected at the event will be invited to make pledges to reduce their environmental footprint.
"It could be small steps or big lifestyle changes," explains organizer Melanie Dennis Unrau.
"They might commit not to fly for the next year or to cycle or walk to work."
Sponsored by Geez magazine and Charleswood Mennonite Church, the morning begins with a walk along Portage Avenue, beginning at 9:30 a.m. from Omand's Creek Park, at the corner of Wolseley Avenue and Raglan Road, and then proceeds to Memorial Park. Marchers will be following a large gold oil drum and a cross, symbols of overconsumption and change.
"Part of the plan is that people should not take motorized vehicles to get to this event and we're asking them not to use fossil fuels on that day," explains Dennis Unrau, editor of Geez.
Although Enns' role as Brother John is to motivate and inspire the gathered congregation tomorrow, the long-time activist and former youth pastor struggles with despair about whether humans will really change their ways.
"I think there is a spirit in our midst that knows the way and is reaching to us and to our consumer, rational minds," says Enns, who studied at a Mennonite seminary.
"Because the word of the spirit is, 'Only take what you need and leave the rest for others.' "
For Epp-Tiessen, the day is about hope that people of faith will do the right thing.
"A primary motivation for me is love and I think a primary motivation for Christians should be love, not guilt."