Mother Teresa, too, startled the world when her posthumous diaries revealed that she was tormented by a continual gloom and aching to see, or sense, God. In 1953 she wrote, “Please pray specially for me that I may not spoil His work and that Our Lord may show Himself — for there is such terrible darkness within me, as if everything was dead. It has been like this more or less from the time I started ‘the work.”’

And yet by this work, she helped many thousands of people. And it’s not always torment. Some live quite contentedly with a patchwork of doubt. Who can possibly hope to understand everything, and to have exhaustively researched all areas of uncertainty? How can we jam the infinite and contain it in our tiny brains? This is why there is so much comfort in mystery.

Just over a month before he died, Benjamin Franklin wrote that he thought the “System of morals” and the religion of Jesus of Nazareth were the “best the World ever saw,” though Franklin said he had, along “with most of the present Dissenters in England, some Doubts as to his Divinity: tho’ it is a Question I do not dogmatise upon, having never studied it, and think it needless to busy myself with it now, when I expect soon an opportunity of knowing the truth with less trouble.” A logical pragmatism.

My local pastor, Tim Giovanelli, a Baptist whose ocean-swimming prowess has lassoed scores of surfers and swimmers into his church, puts it simply: “For Welby, myself and many others, it is not that we have certainty but have seen the plausibility of faith and positive impact it can make. In a broken world, that can be enough.”

If we don’t accept both the commonality and importance of doubt, we don’t allow for the possibility of mistakes or misjudgments. While certainty frequently calcifies into rigidity, intolerance and self-righteousness, doubt can deepen, clarify and explain. This is, of course, a subject far broader than belief in God.

The philosopher Bertrand Russell put it best. The whole problem with the world, he wrote, is that “the stupid are cocksure while the intelligent are full of doubt.”

Of that at least we can be certain. I’m pretty sure, anyway.

Julia Baird is an author, a journalist and a television presenter with the Australian Broadcasting Corporation. She is working on a biography of Queen Victoria.