The question is religion. I do not mean pneuma, spirit or soul. I mean the earthly house which is its cage and from which the hierarchs, those representatives of God, rule over heart and mind. Why did I turn my back on the church and why does it now hold such allure?

I have been thinking a great deal about my paternal grandfather's miraculous return to sight. He'd been blind and living on the island of Tinos in the Aegean Sea. One morning, a nun stood him before the icon of the Virgin Mary that was reputed to perform miracles. ‘Can you see anything?' she asked him. For seven years the nun had been asking this question. The answer was always in the negative. But today something did indeed happen. From out of the darkness that surrounded him, my grandfather saw a golden light approaching. Within this light stood the Virgin in all her glory. With a cry, Grandfather is said to have fallen to his knees, weeping. When he dared open his eyes again, his sight had returned.

I remember, too, that while growing up in Turkey I was inspired to become a priest of the Greek Orthodox Church. It wasn't that I wanted to be a spiritual fireman, rescuing souls from the flames of hell. No, more than likely it was the sense of occasion, grand ritual, extravagant dress and iconography that made such an appeal to my senses. But, in the dust of vanity, was something else hiding? An instinct perhaps toward the numen, planted there by my mother's side of the family that had been high up in the Greek Orthodox Patriarchate of Istanbul.

Perhaps the answer lies in the photograph that has obsessed me for weeks. I can't shake the image and I don't know why. But I suspect that if I were to write about it, a kind of instinct will come into play. What I'm going to write about, this mysterious attraction, is already there, hiding, waiting to be brought into the light.

For days I sat with the image beside me or held it up in the dark dome behind my closed eyes. I submerged myself in it until our dialogue began to break up like poor-transmission radio. The more I looked at it, the less there was to see. Finally, the image dissolved before my eyes. Paradoxically, it was only when meaninglessness asserted itself that the transmission was reinstated.

The photograph is of a ten or eleven-year-old boy. From the cast of his features he reveals himself to be a Greek of Asia Minor. His lips are slightly pursed as if to utter a prayer or to kiss the icon before him. His clothing is Sunday best, a little man going about the business of worship. From behind, candlelight touches his left shoulder and back like a benediction.

From the caption we know that the year is 1957. The boy is inside a Greek Orthodox church, near Istanbul's Golden Horn. Perhaps the church is down by the water in Fener or up a hill in Beyoglu. We don't know. Ara Güler, the photographer, has not recorded the name of the church that swims in the background like the vaporous body of a phantom.

Ara Güler is a photographer of the first order, a member of the Magnum Photo Agency. As a chronicler of an age and a truth-sayer, his aim is to capture a tremulous moment of endangered aboriginal culture and to telegraph it to a future devoid of its presence. What makes him unique among photographers is that his camera is an extension of his eye and his eye the heart and soul of the camera. In him, man and machine are wed, inseparable. He records a fading past even as he is already steeped in a science-fiction future. The black and white image, the fruit of the union between man and machine, is a state of mind. Foremost it is what Ara Güler implanted into the womb of his camera. The rest is up to the chemistry that begins its mysterious work in the alchemical bath of the dark room.

What rises to the surface is a portrait of devotion that is also more than itself. This photograph of a Greek boy in a church is a time capsule; the past grafted onto the back of the future. Like the Egyptian pyramids, the camera is a resurrection machine, a maker of immortals. The printed image freezes a likeness and sends it across time and space exactly as it had been; intact and unchanging, just as the pyramid shot Pharaoh to that still point in space considered by the ancients to be eternal.

Since the year is 1957, we know that it is only two short years after Greek Cypriots massacred scores of Turkish Cypriots. No one could have been too surprised when Turks retaliated by washing the streets of Istanbul with Greek blood. Once again Levantine Greeks abandoned Constantinople, their spiritual capital, for other shores. Tears and wails emanate from behind walls thought to be impregnable. History repeats itself.

Istanbul is said to be the city in which the past walks hand in hand with the present. Only of late, as Ara Güler's photographs of this Gordian knot of a city testify, the past has been getting a little lost, unable to find its way back through the labyrinth of newly sprung streets and developments. The celestial city obscured by a crasser, louder, modern city laying itself atop the old. Which is as it should be. Istanbulfollows the natural order. Progress, a headlong forward movement into the future. The only way to forget.

Looking to the future, the boy's gaze says it all. ‘Who are you?' he seems to be asking Ara Güler. ‘Why are you photographing me in this house of God? What purpose will the picture serve?'

The boy's submission to the augmented eye of the photographer becomes an act of faith. He has put himself in Ara Güler's hands much the same way as he puts himself in the hands of the Virgin, for better or for worse. He has the look of someone who believes no other option exists. History and the vicissitudes of life may have shaken his faith in a stable world, in redemption, in a life beyond. Despite everything, devotion sparks in him.

Those who witness the Orthodox liturgy are struck by its unashamed appeal to the senses. The central purpose of the liturgy is the consecration and distribution of the bread and wine that constitute the body and blood of Jesus Christ. But the incense, the chanting, the vestments and ritual movements of the priest, and the icons hung everywhere are not mere embellishments. They aim to create a sense of the transcendent beauty of Heaven on Earth.

This emphasis on the sensory has its basis in the Orthodox Church's conviction that the world will be transfigured when Heaven is established on Earth at the end of time. Far from denying the beauty of God's material creation, the liturgy sanctifies it. That's why, when one enters an Orthodox church, it is like seeing for the first time.

Because the church is the living body of Christ, the boy's act of devotion literally places him inside the Son of God. The mortal boy is of Him and distinct, mortal and immortal, a conundrum, which only the ultimate transcendence of the many levels of faith can bring to a resolution.

The icon, that defining symbol of Orthodox Christianity, is not merely a representation of the individual saint or patriarch depicted. Refined to a never-changing series of symbolic gestures, it is the literal manifestation of a divinity. Therefore, to stand before the icon in prayer or contemplation is to look through a window into heaven. The mortal contemplating the immortal, and vice versa.

The boy in the picture is a supplicant before the iconostasis, looming up and around him – the medal-laden breastplate of God, descending from heaven to touch its feet upon the earth, separating the proletarian nave from the mysteries celebrated by initiates in the sanctuary.

In the wild darkness behind the boy, scenes of Byzantine suffering and exultation are suffused with inner light. These objects of veneration are removed in time and space from the worshipper, yet ever present, eternal. Like the photograph, on going. Yet not of eternity because the year of the boy's capture, his imprisonment within the confines of the photograph, belongs to a specific time. And the fathers of the church lived in a past remote beyond measure. Yet, paradoxically, steeped in the present, too.

Time melts. I see now that the photograph is a window that looks into a paradisiacal garden suffused with that deep subliminal eloquence residing behind the boy's interrogatory gaze. The light that lives there is a searing brilliance, burning out from under the rich blacks and muted greys of the foreground to create white spaces or voids through which the secret life of the picture asserts its self. The intensity of this light threatens to obliterate the image from within, like concentrated heat destroying a piece of celluloid film.

Most obviously it's in the electric light that is suspended above the boy, hovering like a seraphim, and in the candles to the right that sear the image. From there, like a forest fire, the light leaps to the offerings strung in front of the icon of the death of the Theotokou, the Mother of God. Significantly, it then coalesces on the small crucifix burning white hot on the chest of the patriarch in the icon propped up before the boy.

And now you realise what Ara Güler is up to, what potential he must have seen in this coming together of variables that day in 1957. The boy is a conduit, suspended between the temporal and the spiritual, the real and the unreal, the dead and the living. The minute this registers, you receive a thrust that carries you above the heads of the angels. The photograph ceases to be about surfaces and mark-making, and becomes a search into what lies behind appearances. By sealing the boy's lips with a smudge of darkness, Güler unleashes the eyes. As we concentrate on them, they turn into wide-open mouths that allow us to see and to be seen. To speak and be spoken to.

By what, I hesitate to say. I was brought up Greek Orthodox; it's true. In childhood, I too combed my hair from left to right and put on a little suit and walked down the long cobbled streets of my island village to church. I stood before the icon, just as the boy does in this photograph. At some stage, however, I lost my parents' religion and now wander the shopping mall with an empty wallet. If, by some miracle, I were to find my way back again, I'm sure it will be by accident, in a most gratuitous manner. It will have to be a repetition of something that happened a little while ago in Istanbul.

I was in the Church of the Panagia in the Beyoglu district. I'd gone early one Sunday morning to light a candle for an ailing distant cousin in America. Why, I don't know. It's not as if I believe in miracles or the especial attention of saints. All the same, I went and found comfort in performing the familiar rituals that are as much a part of me as my breath, and as alien.

Afterwards, as I was leaving, I saw an Ethiopian boy pressed against the holiest woman in Christendom. So ardent was his embrace that it seemed certain the Virgin was no longer immaculate.

This flagrant display of adoration took place in the narthex of the church, in front of the side entrance where candles can be bought for less than a million lira. In his right hand the boy was holding a burning candle that seemed fashioned out of curdled cream. His left arm was raised over his head and the palm of his hand pressed flat against the glass of the icon, as if grasping a delectable bosom. With his eyes closed, he ardently kissed the Virgin just above the navel. Lower down, his chest rested on the frame and his sex seemed welded to the wall.

His stillness was reminiscent of saints and visionaries frozen in acts of adoration. As I looked on, it occurred to me that I was witnessing the root of all conflict: the sacred and the profane: Ecstasy. He was a statue paralysed by his desire to converge with the Immaculate. From where I stood, it seemed like his face had already melted into the wood and plaster of the icon and the rest of his body was soon to follow. There was no one else about, only me, with one foot in the nave and the other in the narthex. Utter silence, as in a bedroom with the curtains closed.

When he sensed a voyeur, eyes upon him, his limbs flew to life. As he turned to face me, his bones were truly weightless, blown about by the slightest breeze. And in that moment, an indefinable fire leapt from him to me, a cursory kiss behind the eyelids. It was as if I had thrown back dark-green shutters to stand in the morning sun, looking out to a calm yet treacherous sea.

Having experienced his direct communion with the Virgin, the Ethiopian had become an ecstatic sage or hermit. It was writ large on his eremitic face and in that feeling of levitation and ascendancy that swirled about him as he moved. By surrendering himself so utterly, he was ready to break free of the earth's crust. Looking me straight in the eye, candle still burning in his right hand, he brushed past like a dust mote and disappeared in the dark of the church.

Rejoicing, I walked away to mix with the crowds on the narrow boulevard. The immensity of the moment became imperishable. I have often thought that it is the truly sensual who take easily to matters of the spirit. And here was living proof. The Ethiopian's rapturous deflowering of the Virgin was over in a flash. Yet it seemed to go on forever, stretching the fabric of reality, muting all sounds. For those few seconds it seemed that he and I existed in the heart of a fiery planet. His was an incandescent human dare, a Promethean spark, for which the only intermediary was the transcendent flesh and bone body, anointed and dissolving. The drips of hardened wax on the floor at the feet of the icon showed where he had been.