Huge crowds have turned out in the Sri Lankan capital to see Pope Francis celebrate a Mass at which he canonised the nation's first saint.
The Pope urged people to follow the example of 17th Century missionary Joseph Vaz at the service in Colombo.
On Tuesday, the pontiff called for the "pursuit of truth" to promote "justice, healing and unity" after years of war.
Government forces defeated Tamil rebels in 2009 after 26 years of war, in which both sides were accused of atrocities.
The Pope arrived early for the Mass on Wednesday, informally greeting worshippers.
Hundreds of thousands showed up for the sea-front service at Galle Face Green, with many lining up from Tuesday to secure a place.
In keeping with his message of unity for Sri Lanka, Pope Francis urged its citizens to follow the example of Joseph Vaz and learn to overcome religious differences.
The Pope said St Joseph dedicated his life to the gospel message of reconciliation, and showed "the importance of transcending religious divisions in the service of peace".
"Religious freedom is a fundamental human right. Each individual must be free alone or in association with others to seek the truth and to openly express his or her religious conviction," he said.
At the scene: Caroline Wyatt, BBC News, Colombo
The atmosphere at Pope Francis's morning Mass was electrifying. Many of the faithful had camped out overnight to ensure a place. This morning, for hours ahead of the service, families with children of all ages sheltered under sun umbrellas as the heat intensified. They mingled with nuns dressed in all-white robes, sitting under the shade of their own black brollies. Many had travelled from Goa, birthplace of the missionary Joseph Vaz, who became St Joseph.
At the outdoor service by the beach in Colombo, the Pope said the missionary's life showed the importance of transcending religious divisions, emphasising that genuine worship of God bore fruit not in violence or hatred, but in respect for the sacredness of all life.
It was a message that struck a chord with many, after 26 years of fighting and tensions between the majority Sinhalese and the Tamil minority until the conflict ended in 2009. Although the deep scars of ethnic and religious divisions remain, there is a new sense of hope after last week's elections passed off peacefully and delivered Sri Lanka a new president.
The BBC's Yogita Limaye in Colombo says there has been a great deal of enthusiasm for Joseph Vaz's sainthood, not just from the Catholic community of Sri Lanka but also from India's Catholic community.
However, some Buddhist activists have objected to his canonisation and complain that the Catholic Church's violent campaigns during its early years led to the destruction of Buddhist temples.
Pope Francis' visit is part of a six-day tour of Asia which will also see him visiting the Philippines.
Who was Joseph Vaz?
A statue of Joseph Vaz, who was made saint by Pope Francis during a ceremony at Colombo's seafront Galle Face Green, is on stage Wednesday, 14 January, 2015
Born in Portuguese colony of Goa in 1651, arrived in Sri Lanka in 1687
Jailed multiple times by Dutch authorities for helping Catholics, dressed as a beggar to hide himself
Produced prayer books in Sinhalese and Tamil
By his death in 1711 he had earned himself the title Apostle of Sri Lanka
Later on Wednesday Pope Francis will speak at prayers in Madhu in the north, a region which saw some of the fiercest fighting in the war.
The conflict arose from ethnic tensions between the majority Sinhalese and the Tamil minority. The United Nations said both sides committed atrocities against civilians and has approved a war-crimes inquiry. Sri Lanka has so far refused to co-operate.
The previous government consistently denied allegations that it was responsible for the deaths of many thousands of civilians in the final phase of that war.
The Tamil Tiger leaders are dead, so the Sri Lankan authorities have portrayed attempts to investigate as a one-sided witch hunt.
A Sri Lankan Catholic devotee holds a flag bearing the portrait of Pope Francis a day before the celebration of the Papal Mass by Pope Francis in the capital Colombo on 13 January 2015
Crowds started to gather more than 24 hours in advance for the sea-front service
Pope Francis wears a saffron-coloured robe as he sits next to Hindu Ndu-Kurukkal SivaSri T Mahadeva (R) and Buddhist monk Ittapane Dhammalankara (L) during the Interreligious Encounter at the Bmich in Colombo 13 January 2015
Pope Francis met leaders from many religious groups on Tuesday
More than one million Sri Lankans (about 7%) are said to be Christian, most of them Catholic. They include both Sinhalese and Tamils.
About 70% of Sri Lankans are Buddhist, with 13% Hindus and 10% Muslims.
The last papal visit was 20 years ago, when Pope John Paul II was boycotted by Buddhist leaders. But on Tuesday, Pope Francis met a group of Buddhist, Hindu and Muslim leaders, urging reconciliation.
His visit comes amid change in Sri Lanka, where Maithripala Sirisena took office as president on Friday, replacing Mahinda Rajapaksa.
Critics said Mr Rajapaksa's leadership had been marred by increasing corruption and authoritarianism.
Mr Sirisena was a senior minister in the Rajapaksa government when the war was won.
Correspondents say it is not yet clear if his approach to addressing the legacy of the conflict will differ from his predecessor, who is seen as a hero by many Sri Lankans for ending the conflict.
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