The Presbyterian Church must become less formal in order for it to survive, a Presbyterian minister has said.
The comment comes from the author of a book charting the history of Presbyterianism in Ireland.
Professor Laurence Kirkpatrick, an historian, said appealing to young people was an important battle the church must win.
Prof Kirkpatrick's book, Presbyterians in Ireland, was launched at Union Theological College in Belfast.
It chronicles the life and times of the Presbyterian Church and its people since they began settling in Ireland about 1600.
The book contains an external photograph of almost every Presbyterian Church throughout Ireland.
It recounts the establishment of Presbyterianism at the start of the 17th century and looks at "the theological divisions that are at the heart of the dissenting tradition and the influence of the church on the island of Ireland".
Prof Kirkpatrick also analyses the history of the Presbyterian Church at home and its involvement in missions around the world.
His book also looks at each of the presbyteries that make up the Irish Presbyterian Church.