Traditionally many Protestant churches keep October 31st or the Sunday nearest to it as Reformation Day/Reformation Sunday. They do so because the Reformation, i.e. the 16th century Protestant Reformation, is generally considered to have begun on October 31st, 1517. That was the day Martin Luther posted his 95 theses on the doors of Wittenberg Church.

This year Sunday October 31st - next Sunday - will have an extra-special significance for Protestants, especially for Evangelicals, in particular for Lutherans, of whom there are 1,050 in Ireland and some 80 million in the world.

Reformation Sunday this year will indeed be a special day for all Christians and all believers. It will see the authorities of the World Lutheran Federation (WLF) and of the Roman Catholic Church sign a joint declaration on the doctrine of justification.

This doctrine, which addresses the question of how sinners become God's friends, has until now constituted the deepest difference between Evangelicals and the Roman Catholic Church.

The joint declaration is not the sort of agreed statement with which the ecumenical movement is all too familiar: a statement agreed by church representatives and submitted for approval to church authorities but not yet approved by them.

This declaration has already been examined and approved by the church authorities on both sides, not least by the Vatican's Congregation for the Doctrine of the Faith which subjected it to a rigorous scrutiny and delayed its approval for a year.

On the Lutheran side, most of the 124 member-churches of the WLF had already approved it in 1998. Next Sunday's joint signing will "confirm the joint declaration on the doctrine of justification in its entirety".

The declaration will be signed on the Lutheran side by WLF officials and on the Roman Catholic side by officials of the Vatican's Commission for Promoting Christian Unity. The joint signing will be an ecumenical first.

The joint declaration, as paragraph 41 makes clear, does not lift anathemas pronounced by the (Roman Catholic Church's) Council of Trent or the condemnation in the Lutheran Book of Concord. The propositions condemned in the 16th century are still condemned.

What the joint declaration does is to recognise that the propositions then condemned are no longer official Lutheran or Catholic doctrine; so that the condemnations no longer apply, if they ever did. There is some similarity therefore with the events at Rome and Constantinople of December 1965 when the sentences of excommunication pronounced by Roman and Orthodox authorities were not revoked or annulled but "consigned to oblivion" in order to improve inter-church relations between East and West.

THE doctrine of justification has been the subject of research and dialogue for more than 30 years, not only by Lutherans and Roman Catholics but also by Anglicans and Roman Catholics and by the World Evangelical Fellowship and Roman Catholics.

The joint declaration outlines in 44 paragraphs the "consensus in basic truths of the doctrine of justification" which has emerged from this work and which renders the mutual condemnations of the 16th century irrelevant and obsolete.

One quotation from the joint declaration may serve as an illustration. It addresses the Lutheran concern that justification, God's grace and favour, might be earned by good works and the Roman Catholic concern that it might be imputed merely rather than imparted.

In paragraph 15 we read "Together we confess: By grace alone, in faith in Christ's saving work and not because of any merit on our part, we are accepted by God and receive the Holy Spirit who renews our hearts while equipping and calling us to good works."

Outsiders, those with little or no interest in ecumenism, will find it difficult to get excited by this joint declaration, especially if their own spirituality is not particularly church-centred and is more social than personal in its concerns.

Insiders, however, especially those for whom words, however important, are less than deeds, will not find it difficult to say "amen" to this declaration. They will see it as an attempt to express in words what is best practice in both the Roman Catholic and Evangelical traditions of spirituality and devotion.

Those, of course, whose priority is verbal accuracy and loyalty, who put all their trust in formulas, will find it disappointing, as they must find all similar attempts. But the mysteries of religion defy all adequate articulation and Pope John XXIII once famously said that the substance of revealed truth is one thing, its formulation another.

This joint declaration means that what in the 16th century was the main bone of contention between Roman Catholics and Protestants and what has ever since been an obstacle preventing us from praying and working together to promote God's Kingdom has now become a bond of unity.

It will not lead immediately to regular Eucharistic sharing (as distinct from the occasional Eucharistic sharing which is already permissible in certain circumstances) but it should give an immediate fresh fillip to pulpit sharing or exchanging and also to joint action for mission in our unbelieving, unforgiving, unrepentant, unjust, unpeaceful, unreconciled world. It is therefore without doubt another ecumenical milestone.

The place where the joint declaration will be signed on Sunday is not without significance. Augsburg in Germany is where already in 1530 an attempt was made to reach some accommodation.

The attempt failed but it is surely worth recalling that one reason why the Emperor Charles V summoned the Diet of Augsburg was to secure religious peace in order to have a united front against the Muslim Turks.

A united front is also needed today - a united front of all the religions as well as of all the churches and all people of goodwill - to promote the justice and peace of God's Kingdom.

Father Michael Hurley SJ is a former director of the Irish School of Ecumenics and is a member of the Columbanus Community of Reconciliation in Belfast. Next Sunday, along with the Rev Gesa Thiessen, he will preach at the 11 a.m. Lutheran service in St Finian's Church, Adelaide Road, Dublin.