Christians will want to give thanks for the "great blessings" of the Protestant Reformation, the Archbishops of Canterbury and York say in a statement marking the 500th anniversary of the split with Rome.
They also call for repentance for the "persecution and death" and the legacy of mistrust left by the events of five centuries ago.
The annual Week of Prayer for Christian Unity begins on Wednesday. The Archbishops of Canterbury and York have marked the occasion with a joint statement as part of the Reformation anniversary celebrations this year.
The Protestant breakaway from the Catholic church began, according to tradition, when Martin Luther, a German monk, nailed his 95 theses to the cathedral door in Wittenburg. The act prompted a gradual split with numerous Protestant factions tearing away from the authority of the Roman Catholic Church.
The two most senior Church of England figures, who derive their positions from that separation, describe "the lasting damage done five centuries ago to the unity of the Church, in defiance of the clear command of Jesus Christ to unity in love."
Justin Welby and John Sentamu say: "Those turbulent years saw Christian people pitted against each other, such that many suffered persecution and even death at the hands of others claiming to know the same Lord. A legacy of mistrust and competition would then accompany the astonishing global spread of Christianity in the centuries that followed."
They also note the "great blessings" to which the Reformation directly contributed. These include "clear proclamation of the gospel of grace, the availability of the Bible to all in their own language and the recognition of the calling of lay people to serve God in the world and in the church."
The two Anglican leaders call for repentance and a strengthening of relations between Catholic and Protestants.
"Remembering the Reformation should also lead us to repent of our part in perpetuating divisions. Such repentance needs to be linked to action aimed at reaching out to other churches and strengthening relationships with them."
They add: "We therefore call on all Christians to seek to be renewed and united in the truth of the gospel of Christ through our participation in the Reformation Anniversary, to repent of divisions, and, held together in Him, to be a blessing to the world in obedience to Jesus Christ."
