ROME — Two of Pope Francis’ most ardent priorities are environmental protection and Christian unity, and on Tuesday he found way to advance both by leading a service on his newly minted “World Day of Prayer for the Care of Creation” inspired by the Eastern Orthodox churches.

In August, Francis announced plans to mark a day of prayer, saying he was calling on Catholics to follow the lead of the Orthodox who have observed Sept. 1 as a day of prayer for the environment since 1989.

In the wake of the pope’s announcement, Anglicans, Lutherans, and other Christian denominations also embraced the initiative by organizing their own services.

The pope joined bishops, priests, religious men and women, and ordinary laity for a special “Liturgy of the Word” devoted to the environment Tuesday afternoon in St. Peter’s Basilica.

Francis opened the service with a short prayer asking God to “enlighten those in power and [with] money, lest they fall into the sin of indifference, so they love the common good, promote the weak, and love this world we inhabit.”

“The poor and the earth are crying,” Francis said. “Lord, hold us with your power and light, so we protect every life, preparing for a better future, to come into your kingdom of justice, peace, love, beauty.”

The homily was delivered by Italian Rev. Raniero Cantalamessa, the Preacher of the Papal Household and a member of the Capuchin religious order, who insisted that neither Christianity nor religion in general is responsible for the planet’s environmental crisis.

“The map of pollution does not coincide with that of the spread of biblical religion or of other religions, but instead it coincides with that of a savage industrialization, focused only on profit, and with a form of corruption that closes its mouth to any protest and gives in to the dominant powers,” he said.

“No one can seriously serve the cause of protecting creation if they don’t have the courage to point their finger against the accumulation of exaggerated wealth in the hands of a few.”

Cantalamessa also appeared to reject suggestions that population control is necessary to prevent greater environmental damage, arguing that eliminating human beings in order to protect the environment would be “clearly nonsense.”

“It would be as if an immense orchestra was reduced to playing a splendid symphony but in a total vacuum, without anyone to listen and the musicians themselves being deaf.”

Cantalamessa also insisted that the roots of the pontiff’s environmental advocacy are scriptural and spiritual rather than political, particularly citing the legacy of his namesake St. Francis of Assissi.

“Possession excludes but contemplation includes; possession divides, but contemplation multiplies,” Cantalamessa said. “One person alone can possess a lake, a park, and thus everyone is excluded from them, but thousands can contemplate those same lakes and parks, and everyone can enjoy them without taking them away from anyone.”

Cantalamessa noted that the pope’s recent eco-encyclical, Laudato Si’ — which means “praised be” — took its name from a poem from St. Francis. He argued that if St. Francis were alive today, he would have added an additional line.

“Praised be you my Lord for all those who work for protecting our sister and mother earth- scientist, politicians, heads of all the religions, and men and women of good will.”

“Praised be you my Lord for those who together with my name, also take my message and are carrying it to the entire world!”

When Francis initially called for a World Day of Prayer for Creation, he said it was both an attempt to offer believers a chance to reflect upon “the adoption of appropriate lifestyles” and also a “valuable opportunity to bear witness to our growing communion with our Orthodox brothers and sisters.”

Through Twitter, Francis sent his more than 22 million followers a reminder of the occasion, saying “Today [September 1] is the World Day of Prayer for the Care of Creation. Let us work and pray.”

Early on, Francis made both care for the environment and the dialogue between the Christian churches cornerstones of his papacy. Last May he released “Laudato Si’, the first-ever papal encyclical entirely devoted to environmental themes.

The pontiff described the document as an appeal for responsibility to cultivate and protect “the garden in which God has put the human person.”

On the ecumenical front, Francis has had several meetings with Patriarch Bartholomew I, considered the first among equals in the Orthodox world, always calling him “brother.”

An ecumenical day of prayer for creation was first publicly suggested by an Orthodox Metropolitan, John Zizioulas, during the presentation in Rome of Laudato Si’. He attended the launch as a representative of Bartholomew.

At the time, Zizioulas explained that the Orthodox Church has been praying for the environment every Sept. 1 since 1989, and said that an ecumenical approach to the day could mark a step towards greater closeness among the various Christian denominations.