According to the Nottingham Post Muriel Swan, 61, went into Mustard Seed Christian Bookshop to buy a special present for her eight-year-old grandson, Cameron's, First Communion.
The Mustard Seed, which has been running for 30 years, reportedly told her they did not sell Catholic literature, before telling Mrs Swan that "she should get the Pope to open a few bookshops for her".
Mrs Swan told the Post: "The reaction we received left us reeling.
"In this day and age, I was left speechless when she said the shop was anti-Catholic.
"I have come up against discrimination before but all the time I have lived in England this is the first time anti-Catholism has reared its ugly head.
"We just wanted to buy a special Bible."
Chris Stala, the owner of the Mustard Seed, told the paper: "We are Protestant - not Catholic. We don't advertise as a Protestant shop but people who come here just know.
"We are not anti-Catholic in anyway. I am a Christian and she is too but we are part of different sects. You would not get Jehovah's Witnesses coming here either.
"She should get the Pope to open a few bookshops for her because he has plenty of money."
The Equality and Human Rights Commission has refused to get involved with the dispute.
