After the awe-inspiring red rock landscapes of Utah’s National Parks – where it’s easy to forget that mountain biking isn’t the national religion – arriving in the capital is almost a culture shock. Sprawling between the Wasatch and Oquirrh Mountains, Salt Lake City is a bright grid of wide, leafy streets, neat gardens and white picket fences. A smattering of pierced, tattooed, skateboard- wielding teenagers mix into the Saturday afternoon crowds of hand-holding couples and wholesome- looking families. A healthy picture of tradition and modernity.

Keep looking, though, and a few questions begin to surface. Where are all the old people? What’s with all the ads for debt relief? And how hard is it to get a beer in this town? The answer is to be found at the heart of the city, in the gleaming towers of Temple Square, international headquarters of the Mormon Church. Like any traveller, I want to get under the skin of this place and here’s where to start.

Mormonism was born in 1820 in New York when 14-year-old Joseph Smith had a religious vision that Zion, the new Jerusalem, would be built in America. Incorporating his translated gospel, the Book of Mormon, as the word of God along with selected parts of the Old and New Testaments, pioneers of the Church of Jesus Christ of Latter-Day Saints (LDS) arrived in the Salt Lake valley with handcarts and covered wagons to found Deseret, the Mormon State of Utah.

It took some 50 years, and the outlawing of polygamy, for Utah to be accepted into the Union. Today, the ‘traditional family values’ upheld by the LDS are still glaringly evident in a population with a 70% Mormon majority. A youthful population is what you get when you have the highest birth rate in the States. And debt relief’s what you need when you’re raising 10 kids, your wife doesn’t work and you have to pay 10% of your income to the Church.

Good or bad, the effects of the Mormon Church are an inevitable topic of conversation in Salt Lake City – it’s all around you. With his beanie and baggy T-shirt, you could almost believe hostel receptionist Matthew Holt when he says he moved here from Minnesota for the weather. The first clue comes when he explains that the odd characters drifting about the hostel are long-stayers funded by the LDS when their welfare centre closes for the summer. I jokingly ask if anyone’s tried to convert him.

Well, I used to work for the Catholic Church – converting Mormons,” Holt reveals. “There’s a lot of them moving to Wisconsin lately so I’m here to find out a little more about ’em. I’m a counsellor of free will.”

Looking around at the tranquil streets, the children playing in front yards – can it really be such a sinister place?

Holt gives me a knowing look. “They do a good job with their image.”

The smiles that greet visitors at Temple Square are certainly dazzling. Between the ages of 19 and 21 most Mormons spend 18 months in missionary service, and to be chosen to serve here is the ultimate honour. Like a Miss World lineup in sensible shoes, immaculately presented missionary ‘Sisters’ from all over the world work in pairs to give free 30-minute tours of the complex. Sister Panisco from Italy and Sister Merto from the Philippines meet us in front of the flagpoles and launch swiftly into their golden opportunity to tell us about their Church – and a bit about the surrounding buildings.

Learning that the 15 prophets since Joseph Smith have all been American, I remark on this coincidence. The two look at each other, shrug as if they’ve never thought of it before and continue on. “The Assembly Hall was built of solid granite by pioneers in 1877 …” Not all questions are welcome, clearly, but it’s these little quirks that give the insights.

Inside the Tabernacle, we’re given a demonstration of the world-famous acoustics. Back ruler-straight, the tiny distant figure on the stage tears a newspaper into neat strips, then drops a pin onto the tabletop. Without amplification, the sound that reaches the back is so crisp it hurts. There’s a soundproof chamber for kids, assure the Sisters.

The surreal finale takes place upstairs in the North Visitor Centre, where an enormous white statue of Jesus Christ stands, arms outstretched, before a painted backdrop of planets and stars. Issuing from a pink vortex, a soothing baritone offers a nebulous message of love in English and then Spanish. The same Caucasian, blond and blue-eyed Jesus features in a series of paintings lining the stairs as we exit, where a perky Sister New Zealand is taking a visitor’s picture. “Say Jesus!” she beams as she presses the button.

I’m freaked out, slightly baffled and no closer to understanding the Mormon mind. As we finish up with a Q&A in a fake loungeroom, every one of my questions is met with the smiling shield of unshakeable faith. I decline the offer of a home visit, and leave the Book of Mormon on the sidetable. My instinct is to run screaming, but there’s one thing I can’t miss: the famed Mormon Tabernacle Choir. Tomorrow even happens to be Sunday. So bright and early the next day I find myself back in the Tabernacle, fidgeting nervously on an upper pew amid a sea of men who look like bank managers and women who look like home economics teachers. My final chance to see the light.

Begun in 1927, the choir’s weekly performance recently became the longest continuous network broadcast in the world. Today’s Mothering Sunday service is dedicated to the late Marjorie Hinckley – mother of living prophet Gordon B Hinckley. In the programme, her daughter writes with relief that she “looked like a real mother … no foofy hair or spiked heels, just dressed in her typically tidy house dress.” Salvation slips from view as I contemplate this kind of dress code – and then the choir begins to sing.

As the soft, mesmerising waves of sound bathe this vast space, I begin to see the point of it all. The hymns have the soothing familiarity of old-time radio – a blanket of comfort, security, enduring tradition that I could easily allow myself to be wrapped in. Yet the cynic in me can’t help but detect something ever-so-faintly sinister in the silver-haired anchor’s messages of love. He announces that Gordon B Hinckley himself is here with his family and, amid the standing ovation, I recognise his voice as that of the talking Jesus statue.

After the service, the international Sisters are lining up in front of the flagpole. One by one they hold up their country placard and welcome visitors in their native language. Last up is Sister USA. She smiles wide and bright. “Ladies and gentlemen – howdy!”

Polite laughter ripples across the manicured lawns as I walk, quickly and surely, towards the waiting car.

• For more information on the LDS, see www.mormon.org; for another perspective, see www.exmormon.org.”