Believers in the northern hemisphere will be spending eight days in prayer and reflection starting on Monday to meditate on the missionary calling Jesus has for his disciples as a part of the 2010 Week of Prayer for Christian Unity.

Organized by the World Council of Churches (WCC) and the Pontifical Council for Promoting Christian Unity (PCPCU), the annual event brings together believers from around the world in special ecumenical services and daily, personal reflection.

The 2010 theme, chosen in Scotland during preparations for the anniversary of the 1910 World Mission Conference, is taken from Luke's account of Christ's final words before his ascension: "You are witnesses of these things."

"Not everyone naturally makes the link between missionary endeavour and the desire for Christian Unity. Yet surely the missionary commitment of the church must go hand in hand with its ecumenical commitment? Because of our baptism we are already one body and we are called to live in communion. God has made us brothers and sisters in Christ. Is not this the fundamental witness that we are called to?" reads the brochure text for the event.

Week of Prayer 2010 participants are also asked to meditate daily on Luke 24 and how they can remedy church division through their witness. Monday's reflection begins with the theme of "praising the One who gives us the gift of life and resurrection."

In a message delivered Sunday at St. Peter's Square, Pope Benedict XVI called the Week of Prayer a time to "revive the ecumenical spirit."

Benedict said that the annual event "constitutes, for believers in Christ, a propitious time to revive the ecumenical spirit, to meet each other, to get to know each other, to pray and reflect together."

The Week of Prayer for Christian Unity officially began in 1966 as a joint effort between the WCC's Commission on Faith and Order and the Roman Catholic Secretariat for Promoting Christian Unity (now known as the PCPCU). Brochure material for the week of prayer is found on the WCC website and is published in English, French, German, Spanish and Portuguese.