The Archbishop of Canterbury, Dr Rowan Williams, is preaching at the Church of Ireland General Synod.
He is addressing about 600 delegates at the synod in Armagh on Tuesday.
It is the first time that the synod has met in the city.
The Church of Ireland Primate, Archbishop Robin Eames, is also speaking at the event, which is being held over three days.
He said the lack of progress in Northern Ireland's political process was eroding public interest in politics.
"It must be a matter of concern when we are confronted with evidence of public disenchantment with the political process," said Dr Eames.
"Figures of those casting their votes at an election, the results of independent research into attitudes and opinions expressed, particularly by young people, indicate a weariness with that part of the peace process which concerns political agreement.
"Understandable though this attitude is, as the apparent speed of political progress has varied, it is a dangerous and regrettable aspect of community life here at present.
"It further illustrates the urgent need for political progress to replace growing disenchantment on the part of many."