Cardinal Cupich and Greek Orthodox Metropolitan Nathanael led a congregation of about 100 people in the seventh annual solemn vespers for the World Day of Prayer for the Care of Creation at Our Lady of Perpetual Help Church in Glenview Oct. 22.

The service included psalms, a reading from St. Paul’s Letter to the Romans and the creation story from the first chapter of Genesis.

It usually is conducted on Sept. 1, the date that the late Ecumenical Patriarch Demetrios I of Constantinople designated as a day for prayer for “the protection of the environment” for Orthodox Christians in 1989. Pope Francis designated the same day as the “World Day of Prayer for the Care of Creation” for Catholics in 2015.

While the two communities were unable to join together in prayer on Sept. 1 this year, the Oct. 22 date was both the 30th anniversary of Ecumenical Patriarch Bartholomew I of Constantinople and the feast day of St. John Paul II.

At the beginning of his homily, the cardinal read the greetings Pope Francis sent to Patriarch Bartholomew on the occasion of his anniversary, describing their relationship as one of “fraternal friendship.”

Cardinal Cupich cited the cooperation of Orthodox and Catholic Christians to safeguard the environment as an example of working together in harmony, being patient and encouraging one another, as St. Paul encouraged his readers to do.

“For example, on Oct. 4, the feast of St. Francis of Assisi, the Holy Father and the Ecumenical Patriarch joined other Christian and religious leaders at the Vatican to encourage each other as people of faith committed to addressing the climate crisis we now face,” the cardinal said. “Each spoke out of the respective riches of his or her own religious tradition and all arrived at a similar conclusion, we must speak together as religious leaders about the perils of climate change, particularly about its impact on the most vulnerable among us.”

Cardinal Cupich highlighted the interconnectedness of all creation called forth in Genesis.

“In the very first lines of the Bible, we hear the refrain, “and God saw that it was good,” which is repeated throughout the first chapter of Genesis,” he said. “Waters, land, creatures, plants: an interconnected matrix of creation willed by God — all created before humans.”

Metropolitan Nathanael agreed that all creation is inextricably linked.

“We cannot love God or our neighbor if we do not love creation,” he said.

As the climate crisis increases in urgency, the cardinal said, humanity must come together to act now, even though that will mean making sacrifices, which many do not want to do.

“But the world’s great religious and ethical traditions know the value of sacrifice and we can do a great service to humanity by recovering these traditions, he said. It might seem that a society such as ours has lost its capacity for sustained sacrifice, or at least lost sight of the ennobling role that sacrifice can play in our individual and communal lives. But if we look more deeply, we find in the enormous sacrifices that families make for their children a proclamation that sustained sacrifice is in fact all around us.”

Vespers were followed by refreshments and a lecture from architect Doug Farr about finding ways to end the use of fossil fuels.

Farr, who recently launched a 30-year-campaign called “Carbon Free Chicago,” said the sacrifices that come with ending dependency on fossil fuels are mostly financial, at least for people of means. The technology exists to generate electricity from renewable resources, and for that electricity to power homes and vehicles.

However, even having people affluent enough to, say, change their home heating system from natural gas to an electric heat pump will benefit poorer people, because it will lead to cleaner air.

The lack, he said, is in imagination, as humanity falls back on thousands of years of burning things for heat and light.

In Illinois, Farr said, about 28 percent of the fossil fuels — including coal, petroleum products and natural gas — that are burned generate electricity, 25 percent heat buildings and 21 percent power vehicles.

Farr said that will likely change quickly as the threat of climate change becomes more obvious, but the fastest changes will come from individuals and cities.

“Expecting federal government to act urgently, I’ve come to believe, is a stretch,” he said.