Battle lines are set as two opposing Christian groups on the European Union referendum exchanged barbs in an increasingly hostile debate.

Michael Sadgrove, retired Church of England priest and founder of the Christians for Europe blog, accused another Church of England priest and Brexiteer, Giles Fraser of being "wrong politically, historically and theologically" in a letter to the Guardian.

Sadgrove wrote the letter in response to an article by Giles Fraser, co-chairman of Christians for Britain, who said the Protestant reformation provided the "intellectual roots of Euroscepticism".

Fraser wrote in the Guardian: "The EU still feels a little like some semi-secular echo of the Holy Roman empire, a bureaucratic monster that, through the imposition of canon law, swallows up difference and seeks after doctrinal uniformity."

He added: "There are those of us who protest against our laws being crafted by some foreign power, beyond the control of our domestic parliament. Brexit perfectly recycles this defiant spirit of the Reformation."

However Sadgrove argued Fraser was "ill-informed" to cite the EU as a foreign power and said it was wrong to say the reformer Martin Luther was a supporter of the separate national churches.

Sadgrove added: "Theologically, there is no basis at all for the idea of separate national churches. Indeed, Paul's letters are full of references not just to the unimportance of nationality but to the need to work together, with each playing their part and learning and growing together, with an express condemnation of schism."

However Fraser told Christian Today he stood by his comparison between Brexit and the Reformation.

"It's important to see that this debate is not just about economics but about European identity. The question of European identity has been discussed for hundreds of years," he said. "It would be mad to think the reformation was not a contributor to European identity as was the centuries of influence by the Catholic Church."

He added: "This is a debate between people on the margins and people in the centre."

The two groups will take part in a debate ahead of the referendum although no date has yet been set. They are part of a wider effort on behalf of Christians to engage with the question ahead of the referendum on June 23.

The Archbishop of Canterbury has remained neutral on the matter as has the official line of the Catholic Church in the UK. However the most senior Catholic Cardinal in England and Wales, Vincent Nichols, has said he thinks Britain would face "complex problems" if it were to leave the EU.

He added: "There is a long tradition in Christianity and Catholicism in particular of believing in holding things together. So the Catholic stance towards an effort such as the EU is largely supportive."