Keith Urban slammed over detail in his church attire as he attends mass with wife Nicole Kidman and daughter Faith in Sydney

Keith Urban has faced backlash for his choice of outfit while attending church with his wife Nicole Kidman and daughter Faith in Sydney.

The New Zealand-born country singer, 57, was seen leaving the service on Sunday in a long sleeve navy shirt, black pants and sneakers.

But fans slammed the guitarist for attending mass while leaving the top buttons of his shirt open.

'Do your shirt up Keith! You're in church, not a bar,' one person said.

'Since when has it been stylish to wear tattoo-exposing unbuttoned shirt and tatty trainers to church,' another commented.

'Keith needs to button the two top remaining buttons on his shirt. His classic "show my chest and tattoo look" isn't a proper image for church,' a third said.

Another added: 'None of them are dressed for church, perhaps a shopping trip but not church.'

However, some defended Keith's look with one writing: 'I don't think that God would judge people by what they wear or style of hair.'

'They look wonderful. They're in church. I'm glad to see that,' another agreed.

Keith and his wife Nicole touched down in Australia on Saturday to reunite with her extended family for their first Christmas since her beloved mother Janelle's death.

The actress has had a difficult few months since Janelle died aged 84 in September - just hours before Nicole won an award at Venice Film Festival.

She is now preparing for her first Christmas without her mother and flew back to Sydney to reunite with her family as they rally around to support one another.

It is tradition for Nicole to jet back to Australia over the Christmas period and she and Keith often host New Year's Eve celebrations at their Sydney Harbour apartments.

Over the past ten years, Nicole has purchased two penthouses in the exclusive North Sydney Latitude building and then combined them to make a mega-apartment.

While back in Sydney this Christmas, Nicole will no doubt be reuniting with her younger sister Antonia, 54, and her family for the holidays.

Nicole and Keith married on the 25th of June, 2006, after meeting at an event the previous year.

The couple tied the knot at the Cardinal Cerretti Chapel in the grounds of St Patrick's College in Manly, Sydney.

A-list guests including Hugh Jackman and Deborra-Lee Furness, along with Naomi Watts and director Baz Luhrmann.

Nicole's two adopted children, Isabella, 31, and Connor, 29, who she shares with ex-husband Tom Cruise, acted as bridesmaid and usher.