The Archbishop of Canterbury, the Most Rev Justin Welby, has disclosed that he questions whether God exists.
Britain's most senior churchman, who is effectively the leader of almost 80 million Anglicans worldwide, admitted that there are moments when he asks himself "Is there a God?" and "Where is God?"
He also said Christians cannot explain why suffering exists in the world but that the answer was faith.
His remarks came in an interview conducted as part of a service at Bristol Cathedral, during a visit to the diocese.
Asked whether, despite his high profile as a religious leader, he ever struggles with doubt, the archbishop said: "Yes I do.
"I mean, there are moments, sure, where you think 'is there a God?', 'Where is God?'"
He added that there were moments when he was struck with doubts even while praying, including during his regular morning jogs near Lambeth Palace.
"I love the psalms, if you look at Psalm 88, that's full of doubt," he told the congregation.
"The other day I was praying over something as I was running and I ended up saying to God 'Look this is all very well but isn't it about time you did something - if you're there' - which is probably not what the Archbishop of Canterbury should say."