When water started trickling down a statue of Jesus Christ at a Catholic church in Mumbai earlier this year, locals were quick to declare a miracle. Some began collecting the holy water and the Church of Our Lady of Velankanni began to promote it as a site of pilgrimage.

So when Sanal Edamaruku arrived and established that this was not holy water so much as holey plumbing, the backlash was severe. The renowned rationalist was accused of blasphemy, charged with offences that carry a three-year prison sentence and eventually, after receiving death threats, had to seek exile in Finland.

Now he is calling for European governments to press Delhi into dropping the case. And on the first leg of a tour around EU capitals on Friday, he warned that India was sacrificing freedom of expression for outdated, colonial-era rules about blasphemy.

"There is a huge contradiction in the content of the Indian constitution which guarantees freedom of speech and the blasphemy law from 1860 under then colonial rule," Edamaruku told the Guardian in an interview in Dublin.

"This blasphemy law can affect anyone in India – even a girl recently who wrote on Facebook against closing down a city because of the death of a famous local politician. She was prosecuted under the blasphemy law and another girl who 'liked' her comment on Facebook was also arrested and then charged with blasphemy."