LONDON – The neophyte holders of two of Christendom’s most venerable posts met for the first time Friday and spoke of fostering unity and understanding between their sometimes rival branches of the faith.

Pope Francis and Archbishop of Canterbury Justin Welby exchanged warm words at the Vatican even as they acknowledged that relations between the Roman Catholic Church and the Anglican Communion had historically been, as the pontiff put it, “not without pain.”

The Anglican Communion has its origins in the split from Rome by Henry VIII of England, who sought to divorce the first of his six wives but was refused permission by the pope.

Francis, a lifelong cleric, and Welby, a former oil executive, were installed as heads of their respective churches in March, within two days of each other. Both men have said that they neither wanted nor sought their current jobs, which were thrust on them by others.

Together they are the spiritual leaders of nearly 1.2 billion Christians, 1.1 billion of whom are Catholics. The Anglicans include members of the Church of England and the Episcopal Church in the United States.

Although the two denominations have made a push in recent years for greater dialogue and common cause, tensions bubbled over again in 2009 when then-Pope Benedict XVI offered theologically conservative Anglican priests and congregations a path, in effect, to defect to Rome.

Francis said Friday that he was grateful “for the sincere efforts the Church of England has made to understand” the reasons for his predecessor’s controversial move, which angry Anglicans saw as little more than a divide-and-conquer ploy.

Welby also reached out with emollient words and an acknowledgment that strife between the two churches was a poor witness to a common faith.

Besides his meeting with Francis, Welby visited the tomb of St. Peter beneath the monumental basilica named for the apostle in Vatican City, and prayed at the tomb of Pope John Paul II.