Christian unity took another small book significant step closer to reality this week as a group of Protestant churches added its voice to the cause.

The World Communion of Reformed Churches agreed to sign the Joint Declaration on Justification – a document originally agreed by Roman Catholics and Lutherans in 1999.

It's a significant moment because the dispute over justification – how Christians are made right with God – was one of the main disputes of the Reformation. 500 years since the beginning of that major split in the church, the WCRC has added its voice to the Lutherans and Roman Catholics in declaring that aspect of the argument over.

The WCRC is a significant body, representing around 80 million Christians worldwide including Congregational, Presbyterian, Reformed, United, Uniting and Waldensian denominations in over 100 countries.

Orthodox and Anabaptist Christians were witnesses to the ceremony in Wittenberg, home of Martin Luther, while Lutherans and Methodists were involved in the ceremony. Pope Francis and Ecumenical Patriarch Bartholomew sent messages of support.

Catholics and Lutherans agreed a, 'consensus in basic truths exists between Lutherans and Catholics. With the WCRC adding its voice to that sentiment, unity between Christians is one stage closer.

'Today we are not only signing a statement, we are building a church together,' said Rev Najla Kassab from Lebanon, who preached a sermon at the event.

'Today is a historic day,' said Jerry Pillay, president of the World Communion of Reformed Churches.