Last November, on so-called #RedWednesday, cathedrals and other church buildings around Ireland were lit up in red as congregations gathered to pray in solidarity with Christians and other minorities who are persecuted for their religious beliefs.
Their suffering often goes unnoticed - most of us go about our business, unaware of the injustice and discrimination affecting them.
I recently had the chance to see and hear first-hand about some of that suffering when in mid-December I travelled to northern Iraq with Caoimhe de Barra and Sean Farrell of Trocaire to meet families who were terrorised from their homes by Isil back in 2014.
Many have still not been able to return home - be it to to Mosul or to other villages on the Nineveh plain. They are deterred by the presence of unexploded landmines - but more so by fear and uncertainty about the future.
We brought them the prayers, thoughts and hope of the people of Ireland.
The shocking destruction evident in the town of Batnaya brought tears to my eyes. Some 80pc of it lies in ruins; family homes are burned and looted, shops and businesses in tatters; the church and convent buildings destroyed and daubed with hateful graffiti. Even the town's graveyard is desecrated, crosses and gravestones smashed to pieces.
How could anyone do this? How will these families ever piece their possessions and lives back together?
But the human spirit is strong - and made stronger by faith in God's grace and by the outpouring of human compassion and charity.
In the nearby village of Teleskof, I met Fr Salar Boudagh and members of his parish council. Together they have led their people towards recovery and the building of new future. Some 900 homes in the parish have been reconstructed with the help of foreign aid, but more so because of the courage and determination of a people who walk by hope and by the light of Christ that overcomes the darkness of evil.
One grandfather related how many of their young people have already left for Europe, the US and Australia. He has two granddaughters - in Chicago and Brisbane - and talks to them often via Skype. They want him to come and join them. He will not go.
"I'm not leaving", he says, "this is where we are from and our people before us. I will die here and be buried with my family. Christians have lived in these plains since the first century. How can we leave now?"
Sadly though, many are leaving. The Christian communities of the plains of Nineveh in ancient Mesopotamia - first evangelised by the apostles Thomas and Thaddaeus - may be among the earliest in the world. People here still speak Aramaic, the language of Jesus. But their numbers, and those of other minorities - like the Yazidi Muslims - are in steep decline.
Since the fall of Saddam Hussein and the rise in the region of al Qaeda, the Christian population in Iraq has shrunk from more than one and a half million to 200,000-300,000.
The recent Religious Freedom in the World Report 2018, published by Aid to the Church in Need, found significant religious freedom violations in almost a fifth of all countries examined. It observed that "aggressive nationalism, hostile to religious minorities, has worsened," together with "increasing evidence of a curtain of indifference behind which vulnerable faith communities suffer".
Worryingly, the report commented that "in the eyes of western governments and the media, religious freedom is slipping down the human rights priority rankings".
What to do? The church in northern Iraq is already tirelessly working on the ground. We met Archbishop Bashar Warda in Erbil - he is a Redemptorist who lived some time in Dundalk while learning English. He explained how their immediate response to the crisis was to set up refugee camps on church grounds to provide shelter, food and clothing for displaced families and then to find more dignified accommodation for as many households as possible.
With the help of Trocaire and other agencies, he was also able to provide a healthcare clinic and education for displaced children and young people.
Today his priorities have shifted. As many families have at last been able to return to their villages following the defeat of Isil, he plans to restore long-term dignity by rebuilding livelihoods and increasing job opportunities as well as by fixing up homes and church buildings.
He is encouraged by the signing into law in the US of the Iraq and Syria Genocide Relief and Accountability Act.
This bipartisan law, supported by both Republicans and Democrats, will hopefully trigger the massive capital investment necessary to rebuild the fabric of the towns and villages of minorities that were almost wiped out by persecution.
But Archbishop Warda has no illusions. He realises the deep psychological scars of separation, trauma, and suspicion of neighbours cannot be healed by dollars alone.
He appealed for our prayers and for ideas to help them repair the human cost, to give his young people purpose and a reason for hoping, to explore the seemingly impossible task of long-term reconciliation and peace-building.
His people are highly skilled and resourceful - but naturally they are nervous about investing at this point in anything beyond simple survival. I visited the new Catholic University of Erbil and heard the hopes of the young people, some of them anxious to learn and lead their peers towards a brighter future. I saw the new Catholic hospital which is nearing completion.
The school, hospital and university all need teachers, nurses and doctors to inspire and develop the skills of these young people who have lost several years of their education and who continue to experience horrendous flashbacks to the nights they fled their homes amid screaming and the deafening sounds of bullets and bombs.
At the seminary, 14 young men are studying for the priesthood. They have no illusions about the challenging vocation to which God is calling them. Priests in northern Iraq know they have to be true shepherds for their people - spiritual and community leaders, peace builders, reconcilers, men of great courage and resilience.
I spoke to these young men about Father Ragheed Ganni, a former student of the Irish College in Rome, who was martyred after celebrating Mass in Mosul in 2007. Pope Francis met his family on stage at Croke Park in August during the World Meeting of the Families. His attackers shouted as they killed him: "Why are you still here? We told you to close the church."
Following our visit to Iraq, #RedWednesday will never be the same for me again. I now realise that the story of persecution also includes inspiring the triumph of hope over adversity, and that the solidarity, compassion and charity of Irish people can help bring light into the darkness facing our brothers and sisters thousands of miles away.
Archbishop Eamon Martin is Archbishop of Armagh and Primate of All Ireland