Large supermarkets have insisted that extra "browsing time" on Christmas Eve was designed to help frantic shoppers rather than to squeeze last minute cash out of them.
Several large stores, including Tesco, Sainsbury's and Asda are allowing customers to enter their premises half an hour early to fill their trolleys.
Under current legislation, shops can only trade for six hours on Sundays - and this includes Christmas Eve.
Figures in the church and those representing small businesses were among those who are unhappy about the Sunday hours.
The Bishop of Worcester, the Right Reverend Peter Selby, is reportedly against the practice.
Steve Jenkin, spokesman for the Church of England said: "It is the workers in the shops we are concerned about, especially on Christmas Eve.
"The costs to family life and stability, the health of employees and the contribution of small retailers to community cohesion outweigh any potential benefits."
Mr Jenkin said opening to allow extra browsing time was not illegal, but added: "We would argue against any extension of trading hours on a Sunday. I do not like it, I think it is silly but it is Christmas Eve and people can shop on Christmas Eve if they want to."
Martyn Eden, of the Keep Sunday Special campaign, said it was a ploy to make more money at the expense of smaller shops. "It is a grey area and it is bending the rules." he said. "It is not breaking the law but it is taking trade away from the small shops, and it does seem to me that they don't need to do this. They are making enough money anyway."
But the supermarkets defended browsing and said they were simply giving people more time to get ready for Christmas. A spokesman for Asda said: "For many English and Welsh customers there just doesn't seem to be enough time in the days up to Christmas Eve. By introducing half an hour browsing time we are just giving them a helping hand."
