The symbolic leader of the worldwide Anglican Communion said Monday he received news of Roman Catholic leader Pope Benedict XVI's resignation "with a heavy heart."
In his position as Archbishop of Canterbury, Rev. Welby is also the principal leader of the Church of England, a role which he officially took up last week.
Pope Benedict announced his retirement on Monday citing "advanced age," while adding that his mental and physical strength had "deteriorated" to the extent he felt he could not adequately perform his duties as the leader of 1.1 billion Catholics worldwide.
"It was with a heavy heart but complete understanding that we learned this morning of Pope Benedict's declaration of his decision to lay down the burden of ministry as Bishop of Rome, an office which he has held with great dignity, insight and courage," said the Rt. Rev. Justin Welby in a statement.
Rev. Welby said he and Anglicans around the world gave "thanks to God for a priestly life utterly dedicated, in word and deed, in prayer and in costly service, to following Christ."
He recalled the Pope's visit to the United Kingdom in September 2010, noting that at the time Pope Benedict "showed us all something of what the vocation of the See of Rome can mean in practice – a witness to the universal scope of the gospel and a messenger of hope at a time when Christian faith is being called into question.
Rev. Welby also remarked on the Pope's teaching and writing, saying "he has brought a remarkable and creative theological mind to bean on the issues of the day."
"We who belong to other Christian families gladly acknowledge the importance of this witness and join with our Roman Catholic brothers and sisters in thanking God for the inspiration and challenge of Pope Benedict's ministry," he said.