Coleman said Kidman, 39, and Urban, 38, had a "mature love."
"You've got to rely on their maturity and knowledge of each other, and I'm impressed," the priest told Australian media on Friday.
Coleman said he would lecture the couple on the secret of keeping love alive. "Make time for each other, do romantic things together and never part without kissing," he said.
Kidman, who won a 2002 Academy Award for her role in the film The Hours, had a very public divorce from actor Tom Cruise in 2001, ending their 10-year marriage. The two have remained friends, sharing custody of their two children.
Kidman and Urban, both Australians but born overseas, met in 2005 at an awards dinner held by the Australian government in Los Angeles honoring the two of them.
They arrived in Sydney on Monday, saying they were to marry, sparking a paparazzi frenzy to gain a photograph of the couple and discover their wedding venue.
Kidman installed security at her Sydney harborside home, but has remained accessible, delivering a daily photo opportunity. She and Urban even sent the paparazzi case of cold beer.
But the paparazzi have not been so friendly toward each other, with two photographers fighting outside a Sydney children's hospital Kidman was visiting.
By Friday, most media outlets had agreed the venue must be Cardinal Cerretti Memorial Chapel inside the old St Patrick's Catholic seminary overlooking Manly Beach.
The reason? A large white marquee had been erected during the week. But there was no official confirmation.
What was revealed was that the wedding will be a simple affair. "It's a simple Catholic marriage and will not be overly long. It will be inside an hour," said Coleman, who has been a friend of the Kidman family for 30 years.
"It will be the traditional prayers, quite simple, but very sincere," Coleman told The Australian newspaper.
The Sydney Morning Herald said a source close to the wedding had revealed that the statuesque blonde Kidman's dress would be minimalist, white, with a hint of old-world romance.
The Australian newspaper said a Sydney Symphony Orchestra quartet would play as Kidman walked down the aisle, while The Daily Telegraph said Urban would serenade his new wife.
Urban won a Grammy in 2006 for best male country vocal performance on the song "You'll Think of Me."
Guests include Naomi Watts, star of King Kong and longtime Kidman friend, X-Men star Hugh Jackman's wife Deborra-Lee Furness and possibly Russell Crowe. Kidman's children, Isabella, 13, and Connor, 11, will be bridesmaid and usher.