We don't ask directions from a tourist. Nor do we look to a professional athlete for informed political commentary. So, why expect spiritual guidance from a musician? There are countless examples of modern-day pop stars who flaunt their spiritual credentials: from Bono to Bob Marley and from Carlos Santana to any rapper you care to name. Perhaps it was ever thus – the connection between music and religion is ancient. Yet in the modern idiom, apart from gospel music, it could be argued that it all began around 40 years ago when the notion of weaving together spiritual and musical pursuits first gathered momentum. One musician in particular helped push the idea into general acceptance – jazz saxophonist John Coltrane.

At the height of his career, in the 50s and 60s, John Coltrane was to many the sound of the future – his brittle, vibrato-less saxophone style destined to become one of the most pervasive, instantly recognisable in music. His signature sound projects a soulful, searching quality that anyone can hear and embrace, far beyond the jazz circle. Today, he commands a universal appeal and respect matched by very few musicians in any genre, anywhere.

Coltrane, born in 1926 in a small town in North Carolina, was exposed to a rich mix of religion and music from a young age. His mother Alice sang and played piano, his father John dabbled on string instruments, and both were the children of Methodist ministers.

A significant influence was his mother's father, Reverend William Blair, who lead a church, founded a school, and indoctrinated the young Coltrane in the ways, words and rhythms of the Methodist tradition. At an early age he voluntarily stood up in his pew one Sunday, and publicly declared himself a member of the church.

A quiet and intense adolescent, he moved to Philadelphia in 1944, studied music and began playing a variety of styles – swing, rhythm-and-blues and the new sound of bebop. He also developed a heroin habit. In 1955, he joined trumpeter Miles Davis's quintet and was thrust into the national spotlight for the first time. By 1957, his 'junkie shit' (Miles's words) was seriously impeding his ability to perform and he was tossed out of the band.

It was a blow that returned him to the path he first set foot on as a youngster.

"During the year 1957," he later wrote, "I experienced… a spiritual reawakening which was to lead to a richer, fuller, more productive life." What had been the seed of a 'live right, do right, play right' philosophy in his adolescence, bloomed with his withdrawal from narcotic dependency. But there was more to it. As he threw himself back into his music, and blossomed over the next 10 years from featured sideman to bandleader to musical legend, Coltrane revealed (in a privately recorded conversation in 1958) that he had also come a long way in his spiritual outlook.

"After I got around [my] late teens, I started breaking away… I'd question, you know, [my] religion. About two, three years later this Muslim thing came up… When I saw there were so many religions… you know, it screwed up my head."

By the mid 50s, Coltrane was well on his way to constructing his own spiritual apparatus – one that drew from a number of sources. Fellow jazzmen recall him sharing books like the Bhagavad Gita, the Torah and the Autobiography of Guru Yogananda. Music-making played a particularly important role in this spiritual system: "I think that the majority of musicians are interested in truth," he said. "They've got to be, because saying a musical thing is a truth… all musicians are striving to get as near certain perfection as they can get."

In 1965 Coltrane released A Love Supreme – his four-part 'gift to God' suite – in which he used his sax, his voice, and his writing to show how music and message could work as one. Printed on the sleeve was a poem, written by Coltrane himself, that betrayed a familiarity with the traditional preacher-speak of American south ("I will do all I can to be worthy of Thee O Lord"), with a more eastern philosophy ("All made from one… all made in one"), and with what we now call New Age ("One thought can produce millions of vibrations"). In some phrases, Coltrane revealed a universal concept that reached to any and all equally – "No road is an easy one, but they all go back to God." As significant was what went unmentioned: no Christ, no recognised church, no organised religion.

Coltrane had been born and raised Methodist, married a Muslim, investigated Hinduism, Buddhism, Judaism, Shintoism, meditation, chanting, and eventually developed a unique composite of all these. Less than a year before his death in 1967, he stated simply: "I believe in all religions."

John's widow, Alice, tells a story: "Once John and I were coming from a concert that he had and it was late in the morning—we got out at daybreak. We heard a couple leaving, and the lady said, 'I have to hurry home because I'm going to church.' Her companion said, 'Church? You've already been to church!'"