Biologist and author of 'The God Delusion' provides voiceover for 'Mysterious 44,' a musical version of Mark Twain's novel

The lights dim, the organ strikes up, a ghostly voice rises towards the heavens as video images of brain scans and scientific calculations slowly swirl – the perfect cue for evolutionary biologist and professional atheist Richard Dawkins to make his operatic debut.

Fans of the secularist campaigner will be disappointed to learn that the author of The Selfish Gene and The God Delusion will not be appearing in costume at the premiere of the composer Kevin Malone's new opera, Mysterious 44, featuring instead as a disembodied voice.

"It was 1490 – winter," Dawkins intones. "Austria was far away from the world and asleep; it was still the Middle Ages in Austria and promised to remain so for ever. Some even set it away back centuries upon centuries and said that by the mental and spiritual clock it was still the Age of Belief."

Dawkins is an experienced lecturer, debater and public speaker, but has not appeared in a theatrical production since taking a leading role in Cecil Cook's comic operetta The Willow Pattern at the age of 13. On hearing of Malone's project, he said he was "a bit mystified, but intrigued". It was clear from the start he would not be taking a singing role, he continued – "I know my limitations" – but as an experienced reader of his own writings was confident in his abilities. "I do quite a lot of reading aloud."

Dawkins is the most unexpected member of the cast in Saturday's performance at the Hallé orchestra's new home, St Peter's in Ancoats. The story of religious murder, deception and an unearthly visitor is based on Mark Twain's unfinished novel The Mysterious Stranger, set in Austria just after the invention of the printing press.

Three young apprentices to a printer meet a strange entity by the river, who calls himself an angel, performs miracles and introduces them to new ideas and technologies. Four singers are accompanied by electronics and a computer-generated voice, which takes the role of the mysterious presence. Dawkins bookends the piece, his recordings of Twain's words heard in the prelude and the final scene.

The novel exists in four versions written between 1897 and 1908, one of which was published in 1916 after Twain's death by his literary executor, Albert Bigelow Paine. An early version of the story was set in Mississippi or Missouri and featured Tom Sawyer and Huckleberry Finn.

According to Jay Parini, professor of English and creative writing at Middlebury College, Twain was not an atheist, but "liked having it both ways".

"In later years, he was hugely critical of the American quest for empire, critical of the Reconstruction era, and harshly critical of American religiosity," Parini said.

"Twain was nothing if not unconventional, and he hated orthodoxy of any kind. I think that Twain always had deep conflicts when it came to the practice of religion, and he probably felt guilty as he feigned a certain religiosity to make his wife feel comfortable. After her death, he felt adrift."

The early versions of The Mysterious Stranger are "very different … in their settings and names of characters and emphases", but "in all versions, Twain attacks the hypocritical aspects of conventional religious ideas". He may have wanted to criticise religion, "but it was simply difficult for him to formulate this narrative – the story eluded him, and it remained unfinished".

"I first read it when I was 10 years old and it haunted me," Malone said. "It's an antireligious story which went completely counter to my Lutheran upbringing. For me, Mark Twain was the author of Huckleberry Finn, of Tom Sawyer and I couldn't imagine he would write something which demonised organised religion and says Satan doesn't exist, God doesn't exist.

"I thought about it ever since, trying to understand what he was driving at. Eventually I realised that the only way to really understand The Mysterious Stranger was to write my own version."

According to Malone, Twain struggled for more than 10 years "to find a way to convince the reader that one doesn't need organised religion in order to lead a good life".

The opera is "first and foremost a piece of theatre," Malone continued, but also a "campaigning piece", arguing that people should choose for themselves instead of being guided by dogma or cultural pressure. "We're not going to solve problems like smallpox, polio or FGM unless we think rationally, work together and we use our imagination, instead of doctrines which prevent us from helping each other."

Malone thought of asking Dawkins to take part after realising the match between his piece and the aims of the biologist's Foundation for Reason and Science. The foundation, which describes its mission as the support of "scientific education, critical thinking and evidence-based understanding of the natural world in the quest to overcome religious fundamentalism, superstition, intolerance and human suffering", has awarded a grant to film Mysterious 44 for distribution in schools and on YouTube.

"Dawkins was my first choice for the part, my only choice," Malone said. "He's the voice of modern, rational society – calm, gently authoritative without being authoritarian, knowledgeable, very warm."

According to Dawkins, Twain was "a man of great, sardonic wit, which one can't help admiring". "Shortly after my first book, The Selfish Gene, was published," Dawkins said, "I had a nice letter from a man called Clemens, inviting me to become a member of the Mark Twain society."

Dawkins was less sure of the power of opera to convert audiences to the secularist cause. "Any of the arts could perhaps persuade," he said. "I don't have a particular knowledge of opera. I suppose it depends on how many people come along." © Guardian News and Media 2014