Tolerating criminal activity is incompatible with administering justice, Northern Ireland's most senior Catholic cleric has said.
Archbishop Sean Brady was addressing a conference in Belfast
The Archbishop of Armagh, Dr Sean Brady, said he hopes politicians will commit to a shared future by putting in place a power-sharing assembly.
Dr Brady said he hoped the assembly would have "full community support for the institutions of law and order".
He was speaking at a conference of peace commissions in Belfast.
He told the gathering of the church's religious leaders from around the world that he was concerned about the failure of dissident paramilitaries to accept the peace process.
"It is accepted that the tolerance of subversive or criminal activity is incompatible with responsibility for the administration or law and order," he said.
"On the other hand, where reasonable assurances have been given that there is a commitment to support just and representative institutions of law and order, and where this is confirmed by all reasonable means, it is difficult to justify the absence of a system of devolved government, especially of a system which does not have responsibility for the administration of policing and justice within its remit."
The Primate was giving the keynote address at the five-day General Assembly of Catholic Justice and Peace Commissions.
His speech debated what Europe could learn from the role of Northern Ireland's church in conflict, the theme of the five-day conference.
About 60 delegates from almost every country in Europe attended, as well as a number of local Protestant church leaders.
Archbishop Brady said there had been a lot of progress in Northern Ireland since the 1994 ceasefires but warned more needed to be done.
"I would just like to say that I welcome all recent initiatives directed at supporting the ability of the loyalist community to develop its social and political capacity," he added.
"What is of continuing concern, however, is the failure of certain paramilitary organisations to state clearly that they have accepted the principle of majority consent in the Good Friday Agreement and that, whatever happens in coming months in the political negotiations, they accept that the use of violence for political ends can never be justified.
"The failure to provide such reassurances is a matter of deep concern for many people at this time."
Crunch political talks aimed at restoring devolved government by 24 November are due to take place in October.