Pope Francis promised on Wednesday to continue to "stir things up" in the Catholic Church as he moves on with reforms and changes that could leave a lasting legacy.
Francis was speaking at the start of a five-day trip to Portugal to attend a global gathering of young Catholics known as the World Youth Day, held every two or three years in a different city.
The trip is taking place in the shadow of Portugal's huge clergy sexual abuse scandal and local anger at the soaring costs for the event.
Speaking to reporters on the plane from Rome, Francis was reminded of when he urged young people at his first World Youth Day, in Brazil, to not be complacent in the Church but to make noise in order to make themselves heard and instil change.
"We will continue to stir things up," he said.
Francis has enacted numerous changes in the Church since his election in 2013, sometimes upsetting conservatives as he has given women more roles and made it more welcoming and less judgmental towards some groups, including members of the LGBT community.
The 86-year-old pope is making his first trip since intestinal surgery in June and uses a wheelchair and cane.
Francis, who seemed in good form as he walked with the help of a cane in the reporters' section of the plane, said he hoped to return to Rome on Sunday "rejuvenated by his encounter with young people".
It is the fourth such event Francis will preside over since he became pope.
In his first speech, to President Marcelo Rebelo de Sousa and diplomats at a cultural centre, Francis said the world was currently "sailing amid storms on the ocean of history", including the tempest of the war in Ukraine, and urged Europe to find the resolve to help end it and other conflicts.
EDUCATION, NOT WEAPONS
He said Europe should divert money spent on armaments and use it to boost education and fund family friendly legislation to help reverse a falling birth rate aggravated by prohibitive costs of housing for young couples.
He also urged Europe to rise to the challenge of "welcoming, protecting, promoting and integrating" migrants, both for humanitarian reasons and as a means of boosting dwindling populations.
He decried "massive numbers of deaths at sea and empty cradles".
The youth event in Portugal, which is about 80% Catholic, comes less than six months after a report by a Portuguese commission said at least 4,815 minors were sexually abused by clergy - mostly priests - over seven decades.
"There will be young people from all over the world and the reality (of abuse) is present in all continents," said Filipa Almeida, 43, who was abused by a priest when she was 17.
"It's a great opportunity for the Church to do something," said Almeida, a co-founder of Coracao Silenciado (Silenced Heart) an association which helps victims.
Francis is expected to meet privately with abuse victims.
A huge billboard raising awareness of clerical sexual abuse was put up overnight in Lisbon hours before Francis' arrival.
Some Portuguese have criticised the event's costs in one of Western Europe's poorest nations where millions are struggling to make ends meet due to low salaries, inflation and a housing crisis.
Francis will also visit Fatima, the town north of Lisbon where the Church believes that the Virgin Mary appeared to three poor shepherd children in 1917.