The philosopher and poet John O’Donohue believed that it is within our power to transform our fear of death so that we need fear little else this life brings. That he has died, unexpectedly in his sleep at 52, robs the world of a genuinely original religious mind who, almost accidentally, became a bestselling writer and public speaker.

For a priest and academic who spent most of his time living in solitude in a remote spot on the west of Ireland, O’Donohue was as startled as anyone else by his success. Not long after he had decided to leave the priesthood - he found himself having “less and less in common with the hierarchy” - his 1997 book on Celtic spirituality, Anam Cara: Spiritual Wisdom from the Celtic World (1997), became a word-of-mouth hit, racing up the bestseller lists.

For a student of Hegel who had written his PhD in German, O’Donohue found it amusing that pop stars and presidents had his book at their bedside, that Hollywood directors and household name actors sought his counsel. It confirmed his view that there is an intersection between philosophy, poetry and theology which can host an audience increasingly exiled by what he called “the frightened functionaries of institutional religion”. As an accomplished poet, he had the literary tools and dazzling vocabulary to speak a language that persuaded you he was right.

His books, emerging every three or four years, were written in a kind of long-form, prayer style which was impossible to read quickly and did not work for everyone. They were the distinct product of a life often spent in meditation and solitude. Not that he was not a gregarious, fun-loving companion, and mesmerising storyteller in the bar, but that his public presence grew from private silence. One of his great influences, the German mystic Meister Eckhart, believed that nothing resembles God like silence and O’Donohue suggested that the highly strung character of western life was explained by the absence of silence. “When you acknowledge the integrity of your solitude, and settle into its mystery, your relationships with others take on a new warmth, adventure and wonder.”

Born in a limestone valley, Caherbeanna, near Blackhead, County Clare, he was the son of a stonemason who, John used to say, “was in that realm of the mystically sacred”. Father evidently passed on the mystical baton to son, who, after ordination to the priesthood, pursued his philosophical studies at Tübingen University, Germany. He returned to mix lecturing in philosophy with parish life. His ecclesiastical superiors were suspicious as much of his personal charisma as of his inclusive theology. In turn he was sceptical of religious leaders who ignored the essential mystical flame of faith in favour of what he called “manufactured coherence”.

In retrospect, it is surprising he remained in the church as long as he did, but those who met him testified that he grew into a kind of spiritual bard, a priestly troubador speaking one day at an Oxford college, the next at a rock festival. His book Eternal Echoes (1998) referencing Augustine and Baudrillard, Dostoevsky and Sartre, explored postmodern isolation and “our yearning to belong”. It so impressed the film composer John Barry that he wrote and named an album after it.

A 2005 study on Beauty: the Invisible Embrace took classical, medieval, and Celtic traditions to argue that we might be alive for reasons other than productivity or consumption. “When we hear some beautiful piece of Mozart or admire a wonderful building we suddenly become present in ourselves,” he said. “That’s unusual nowadays because dishevelment and distraction have become an art form.”

Two poetry collections captured his love for his native landscape, and he was central to a successful environmental action against development on the Burren. Benedictus, a collection of “blessings” composed for defining moments in a post-ritual world, has peculiar poignancy with its carefully crafted lines to help those living with loss. O’Donohue’s lasting epitaph may be the discovery of his writings at a growing number of funerals, offering people of all faith stories and none a means to express their feelings in a new kind of language.

He is survived by his partner Kristine Fleck, his mother Josie, brothers PJ and Pat, and sister Mary.