Richard Holloway had his first taste of mortality in his 20s, when he started going bald. Though no narcissist, he hated the hair loss, and tried to reverse it with pills, then disguise it with an artful comb-over, before cropping the whole lot off. As he says, baldness is not a terminal disease but he thinks of it as “good preparation for ageing and death, the skeleton being the ultimate baldy”. Just as he grew to accept his baldness then, so now, at 80, he has come to accept that he won’t be around for ever.

For most of us, such acceptance doesn’t come easy. Humankind cannot bear very much reality: don’t ask for whom the bell tolls and maybe it won’t. What Holloway acronymises as AAPD – the Anti-Ageing and Postponement of Death industry – has never been busier. Modern medicine prolongs life even when it no longer has quality or agency. The hucksters of cryogenics promise to bring us back even when we’ve gone: for $200,000, the Alcor Life Extension Foundation in Arizona will preserve your corpse at a temperature of -190C then thaw you out on resurrection day (for the cheaper neuro-only option at $80,000 they’ll freeze just your brain instead).

Holloway is dismayed by all this. As a man deeply versed in religion (a former bishop of Edinburgh and head of the Scottish Episcopal Church), he’s familiar with notions of reincarnation and eternal life. But he thinks denial of death spiritually unhealthy. Even if our corpses did come back, suitably defrosted, what kind of reception would we get? Wouldn’t we be treated like freaks or illegal immigrants? And what about the social injustice of only the rich having the resources to outrun death?

He doesn’t downplay the physical adversities of old age, but sees it as an opportunity for self-examination, for “a last shot at reality”. Looking back, he reproaches himself for inattentiveness, lack of curiosity and, above all, impatience: “Getting there was always the point for me – but where’s there?” Regrets, yes he has a few, but he doesn’t overdo the sackcloth and ashes. We have to play the cards we’re dealt; not everything that happens is in our control. Owning up to past mistakes is important but so is self-forgiveness. Gerard Manley Hopkins had it right: “My own heart let me more have pity on”.

Hopkins is among the many poets from whom he quotes, along with WH Auden, Dylan Thomas and Louis MacNeice. Helen Dunmore would surely have been here, too, had there been time to include her last poems, which chime with Holloway’s argument: “I know I am dying / But why not keep flowering / as long as I can / From my cut stem?” And inevitably there is Larkin, with whose “Aubade” he takes issue, unable to comprehend why extinction should be terrifying: “We won’t be there to know we’re not there … so it can’t hurt.” Novels and paintings are also invoked. The book is enriched by its breadth of cultural reference.

Biblical passages are quoted, too, as well as extracts from orations Holloway has given at funerals and weddings. But his tone is less priestly than agnostic – liberal and secular not fundamentalist. Nothing irks him more than religious certainty. “The Church is in danger of becoming a club for strict believers,” he says, a club with no room for doubt, nuance or “the wistful children of unbelief”. Parishioners for whom religion was once a source of spiritual comfort feel alienated by the stridency. Where faith leaders rant against moral decay, what he sees is a society that has, at best, become more tolerant and inclusive. Whatever his nostalgia for times past, he won’t allow himself any geriatric bitterness and resentment.

The purpose of religion, as he defines it, isn’t to preach to the converted, or hector the fallen, but to wrestle with the mystery of existence. There won’t be conclusive answers, because the universe remains unfathomable; Unhintergehbarkeit – ungetbehindability – is its essence. But that doesn’t invalidate the struggle to make sense of how we began, why we’re here and what (if anything) happens next. Holloway is with Keats and his definition of negative capability, prepared to live with uncertainty without any irritable reaching after fact.

The word “God” isn’t wholly absent from the book. But Holloway has seen too much suffering and cruelty to conjure a benign overseer. He recalls presiding over the funeral of a two-year-old boy and, after reading from the relevant section of The Book of Common Prayer (“Man that is born of woman hath but a short time to live”), putting his arm round the grieving mother and saying he hoped that her pain would pass – to which she responded by shoving him off and shouting that she wanted to go on feeling her pain for ever. It was a lesson in how not to console – though when faced with an 11-year-old girl dying from leukaemia he didn’t hesitate to offer her the hope of a life beyond in the “eternal Here and Now”.

Sometimes, as he says, “there is no room for truth”; what’s needed is wisdom and compassion. They are the qualities that shine through this little book. But there’s a fair bit of truth-telling, too.

• Waiting for the Last Bus: Reflections on Life and Death by Richard Hollway (Canongate, £14.99). To order a copy for £12.74, go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min. p&p of £1.99.