VATICAN CITY (CNS) -- Pope Francis' trip to Asia and Oceania in September will be a trip of religious, economic and social contrasts.

Visiting four nations Sept. 2-13, the 87-year-old pope will be making the longest trip of his pontificate, both in terms of distance covered and days away from the Vatican.

The trip will include predominantly Muslim Indonesia and predominantly Christian Papua New Guinea, as well as Singapore, Asia's economic powerhouse, and Timor-Leste, one of the world's poorest nations.

Plans were being made for the trip in September 2020, but everything was halted because of the COVID-19 pandemic.

Pope Francis not only is four years older, but now regularly uses a cane, a walker or a wheelchair to get around.

The 45th trip of his pontificate is expected to focus heavily on interreligious dialogue, ethnic harmony, care for creation, concern for immigrants and gratitude for the work of missionaries and the church's contribution to education and health care.

His visit will begin in Indonesia, which has the largest Muslim population of any country in the world; Catholics account for only about 3% of the population. Then he will move on to Papua New Guinea, where an estimated 98% of the population is Christian. Timor-Leste is the only nation on the itinerary where Catholics are the majority; the Vatican estimates 96% of the population belongs to the church. In Singapore, Buddhists make up the largest religious group -- about 31% -- followed by 20% of the population claiming no religious belief; Christians account for almost 19% of the population and Muslims about 15%.

While from a European or North American perspective all four countries could be considered part of the "periphery" of global Catholicism -- those outlying areas Pope Francis prioritizes when accepting invitations -- he will stick to the largest city in each nation, with one exception: He will spend about three hours Sept. 8 in Vanimo and Baro, towns on the northwesternmost shore of Papua New Guinea.

It's personal, according to Father Giorgio Licini, a PIME missionary and general secretary of the Papua New Guinea bishops' conference.

Writing in Avvenire, the newspaper of the Italian bishops' conference, Father Licini said Pope Francis insisted on going to the outposts over the advice of the bishops' conference and the government because he wanted to visit his friend, Father Martin Prado, a 35-year-old member of the Institute of the Incarnate Word from Argentina, and see the work he and the Incarnate Word sisters have been doing in the remote area.

But Indonesia is the first stop, and interreligious dialogue and "human fraternity" are expected to be the dominant topics.

Divine Word Father Markus Solo Kewuta, an Indonesian official at the Vatican Dicastery for Interreligious Dialogue, said generally Christian-Muslim relations in his homeland are "very peaceful, very kind," but they can vary in different parts of the country, a nation made up of more than 17,000 islands, about 6,000 of which are inhabited.

The country's main Muslim organization, Nahdlatul Ulama, and the Indonesian government both promote official dialogue, peaceful coexistence and simple neighborliness, Father Solo said, but there is a worrying new trend of "ghetto building," or of people looking to live in neighborhoods where only Muslims or Christians live, which decreases mutual knowledge, trust and cooperation.

The priest, who grew up on the predominantly Catholic island of Flores, told Catholic News Service it still is common for members of the Nahdlatul Ulama youth group to volunteer to stand guard outside their neighborhood Christian churches on Christmas Eve and during the Easter vigil to ensure the services take place in peace.

"Unfortunately, these good relations will be always disturbed by the radical or violent acts of people, and particularly also by the politicization of religion," he said. "This really divides nations, societies and religions; friends become enemies. We have experienced this in the past several times."

"We live in a plurality, and therefore we are condemned to dialogue with each other," he said.

In Indonesia, Papua New Guinea and Timor-Leste, Pope Francis also is expected to talk about the religious obligation to care for creation. All three nations have seen accelerating deforestation as the global market seeks tropical wood, and all three struggle to regulate mining while relying on profits from mineral exports.

Pope Francis will not be the first pope to visit any of the countries on his itinerary. St. Paul VI visited Indonesia in 1970 and St. John Paul II went to the country in 1989; on the same trip, St. John Paul visited Timor-Leste, which celebrated its independence from Indonesia in 2002. The Polish pope visited Papua New Guinea in 1984 and again in 1995. In 1986, St. John Paul visited Singapore, though he stayed only five hours -- enough time to celebrate a public Mass, meet government officials and speak to the nation's priests.

Singapore is one of the world's wealthiest countries, and Pope Francis' 46-hour visit will include time with some of the island's poorer residents -- the elderly and sick people cared for at St. Theresa's Home, a nursing home that can serve up to 200 patients.

A 2014 Pew Research Center report ranked Singapore as the most religiously diverse country in the world, but also found a significant percentage of the population claims no religious affiliation at all. Pope Francis' final event in Singapore, before his 12-hour flight back to Rome, will be an interreligious meeting with young people, bringing the theme full circle.