'Reconciliation is fragile flower in cold climate'
In his sermon to the congregation at Down Cathedral, Archbishop Justin Welby said: "The world needs the witness of those who have made the journey from enemy to friend, who are no longer strangers and aliens, who are being built together into an altogether different community in the household of God.
"And if there is any community who knows this, not simply in heads but in hearts, it is here in Northern Ireland.
"There remain huge challenges, because reconciliation is a fragile flower that always finds itself in the cold climate of the human heart, and can only be nurtured by the warmth of love, of fellowship, of mutuality, of the Spirit of God from whom it comes.
"Despite those challenges you have embarked with enormous courage on the long road to reconciliation and you are the symbol of hope for so many around the world.
"Don't give up.
"Make it work.
"It is a gift of God to you for the world.
"It is held in your hands as a treasure.
"It is something that comes from the peace of God."
After the service, the Archbishop laid a wreath on St Patrick's grave, before joining a parade through Downpatrick attended by an estimated 30,000 people.
The Archbishop made the two-mile pilgrimage walk to Down Cathedral from Saul, site of one of St Patrick's first churches, where earlier on the morning of St Patrick's Day he had he presided at a service of holy communion.
As his visit to Northern Ireland draws to a close, this morning the Archbishop breakfasts with a group of young people working in politics, business, church, media and academia to inspire them to be peacemakers in all areas of society and civic life.