A Vatican-hosted conference has called on the Catholic Church to abandon its 'just war' theory, asking Pope Francis to write an encyclical on nonviolence and 'just peace' instead.

The conference, sponsored by the Vatican's justice and peace office and Pax Christi International, the Catholic peace movement, said the just war doctrine has been used too often to justify violence rather than prevent it.

Instead, Catholics should pursue "active nonviolence" befitting the gospel message of peace, they said.

The historic gathering of 80 senior Catholic peace leaders from 20 nations met at the Vatican between April 11-13.

It was the first time the Catholic Church has discussed abandoning the just war theory, which has been advocated for over 1,700 years. At the close of the conference an official statement was submitted to Pope Francis, appealing to "re-commit to the centrality of gospel nonviolence".

What is 'just war'?

The just war theory, developed by early Church Father St Augustine of Hippo, is a Christian ethical system that advocates for war being – in rare circumstances – the most just action.

The theory poses the following question: If we accept the fact that inaction has consequences, is there a point at which inaction is less morally acceptable than action?

Augustine's just war tradition argues that there comes a point where love of neighbour requires action when one neighbour acts unjustly towards another.

It sets out certain parameters for war, but holds that there are cases in which it is permissible, and even necessary. The basic requirements are that it is in response to a great ill, and that its primary intention is to right that wrong.

There are some crucial boundaries set in place to ensure a war remains just:

1. The war must have just cause – in response to a serious wrong.
2. It must be waged under legitimate authority – not simply by an individual.
3. There must be the right intention – justice, rather than economic or military gain.
4. It must be the last resort – aware that the consequences of war always involve suffering and therefore it should not be entered into lightly.
5. It must be proportionate to the threat – not simply using as much force as possible.
6. It must be discriminate as to who is targetted.
7. There must be a genuine hope of success.

It is particular about the type of war and how it is waged. It rules out air raids in an indiscriminate manner, terrorist action that will intentionally kill civilians, and the dehumanisation of prisoners of war through torture.

There has been a significant move within this theological camp toward including a commitment to justice beyond the point where a war is won, recognising the significant impact warfare has on civilians.

OK, so why does the conference want to get rid of it?

They see a fundamental internal inconsistency in allowing violence in the name of the gospel. Instead, they argue that Jesus modelled a life of active nonviolence.

"Neither passive nor weak, Jesus' nonviolence was the power of love in action. In vision and deed he is the revelation and embodiment of the nonviolent God, a truth especially illuminated in the Cross and Resurrection. He calls us to develop the virtue of nonviolent peacemaking," the closing statement said.

The just war theory, by contrast, has "too often... been used to endorse rather than prevent or limit war".

"We confess that the people of God have betrayed this central message of the gospel many times, participating in wars, persecution, oppression, exploitation, and discrimination," the statement added.

"Suggesting that a 'just war' is possible also undermines the moral imperative to develop tools and capacities for nonviolent transformation of conflict."

What do they propose instead?

'Just peace'.

In the context of "tremendous suffering", the conference called on Christians to push for active nonviolence.

They are petitioning for the Church, and Pope Francis, to recognise that "peace requires justice and justice requires peacemaking."

Based on gospel nonviolence, they suggested "a Just Peace approach offers a vision and an ethic to build peace as well as prevent, defuse, and to heal the damage of violent conflict. This ethic includes a commitment to human dignity and thriving relationships, with specific criteria, virtues, and practices to guide our actions."

Rooted in the "unconditional love of God", they looked to Jesus, who "in his own times, rife with structural violence... proclaimed a new, nonviolent order".

The group, who submitted their letter to the Pope, also urged the Church to "lift up the prophetic voice of the Church to challenge unjust world powers and to support and defend those nonviolent activists whose work for peace and justice put their lives at risk.

"In every age, the Holy Spirit graces the Church with the wisdom to respond to the challenges of its time. In response to what is a global epidemic of violence, which Pope Francis has labeled a 'world war in instalments', we are being called to invoke, pray over, teach and take decisive action. With our communities and organisations, we look forward to continue collaborating with the Holy See and the global Church to advance gospel nonviolence."

How will the Pope respond?

Pope Francis, named after the peace-loving St Francis of Assisi, wrote a greeting to the gathering, saying that the "ultimate and most deeply worthy goal of human beings and of the human community is the abolition of war".

He is undoubtedly an advocate for peace. He has declared this year the Jubilee Year of Mercy, explicitly stated that "faith and violence are incompatible" and issues almost-weekly appeals for peace across the globe.

After the Paris attacks, he described God as "weeping" for the state of the world, yet he also said – in the same homily – that "war can be justified for many reasons".

"Everyone of us who participated in the conference left Rome feeling hopeful that Pope Francis will help lead the Catholic Church and the world to a new breakthrough toward peace and nonviolence," said Rev John Dear, a Catholic priest and peace activist who attended the conference.

That peace is on the Pope's agenda is beyond doubt, but whether 'just war' will continue to be is yet to be determined.