The church was used without consultation with the priest
Legal action is being taken against a photographer who used a Cornish village for an erotic photo shoot.
Pictures of models, some of whom were partially-clothed, were taken inside and outside St Michael Penkivel Church near Truro.
Cornwall-based photographer Andy Craddock is the subject of legal action by the priest in charge for blasphemy.
However, Mr Craddock, 43, of St Austell, described the pictures as "art" and said they were not offensive.
Mr Craddock, who moved to Cornwall from London in 2008, said he used the 13th Century church for the shoot because he had seen it in the comedy movie Keeping Mum.
He said he admired the architecture and wanted the pictures to add to his portfolio of fetishist and erotic photography.
He told BBC News: "I can understand why some people would find them offensive and inappropriate.
"But the general feedback has been very positive.
"I never wanted to offend. This is done as art and shows the beauty of women."
The solicitor's letter describes blasphemy as the "publication of contemptuous, reviling, scurrilous or ludicrous matter relating to God, Jesus Christ, the Bible or the formularies of the Church of England".
"Our clients believe that a number of these photographs constitute blasphemous material," it adds.
Andrew Yates, the priest in charge of St Michael Penkivel, said in a statement: "No permission was ever sought by or given to Mr Craddock by the priest-in-charge or by the churchwardens for these photographs.
"I am deeply shocked that Mr Craddock could consider taking action that will inevitably cause great offence."
He said it had cause upset to "those who have connections to the church through being married at St Michael's or through loved ones who are buried in the churchyard".
Jeremy Dowling, a spokesman for the Diocese of Truro, which is supporting the legal action, said the church was used without permission.
"The Church deplores the use of sacred space in this way," he said.
"Whether he's gone in there legally or illegally he is using the setting for an entirely improper purpose.
"By anyone's reasonable standards of decency this is beyond the pale."