A 17th century 'letter from the devil' written by a Sicilian nun who claimed to be possessed by Lucifer, has finally been translated thanks to the dark web.

The coded letter was written by Maria Crocifissa della Concezione at the Palma di Montechiaro convent in 1676, and she claimed it had been scribed by Satan using her hands.

Some 340 years later, a group of Italian computer scientists unscrambled the code using decryption software they found on the dark web, and found it does carry a devilish message - describing God and Jesus as 'dead weights'.

Dark secrets: The letter, written in 1676, has finally been de-coded by group of computer scientists using decryption software they downloaded from the dark web, who found it brands God an invention of man, and Jesus and the Holy Ghost 'deadweights'

Sister Maria Crocifissa della Concezione was born Isabella Tomasi in 1645, but was rechristened once she entered the Benedictine convent at Palma di Montechiaro aged 15.

One morning in 1676, she awoke covered in ink with the mysterious letter in front of her, telling her sisters she had been possessed by Satan and that he had forced her to write a message.

The nuns believed her, and while they - and the generations of nuns who came after them - could not make sense of the code, they displayed it at the convent.

Many people have tried to decode it over the years, but no one has succeeded - until now.

A team at the Ludum Science Centre in Catania, Sicily, used a program they found on the dark web to unscramble the letter.

Speaking out: It was written by Sister Maria Crocifissa della Concezione at the Palma di Montechiaro convent, and while she said it was 'from Satan', it's not been proven until now

'We heard about the software, which we believe is used by intelligence services for codebreaking,' said Daniele Abate, director of the centre told The Times.

'We primed the software with ancient Greek, Arabic, the Runic alphabet and Latin to de-scramble some of the letter and show that it really is devilish,' he said.

Sister Maria had become very adept at linguistics during her years at the convent, and scientists believe the letter is in fact written in a language of her own invention - a mishmash of the alphabets she had come to know.

Using that theory as a base, the team loaded the software with any language she might have come across: Latin, ancient Runic Greek, modern Greek and even that of the Yazidi people.

By identifying characters in the letter similar to those of the alphabets that Sister Maria would have known, scientists could start making sense of her words.

The group translated 15 lines of the letter and found that it discusses the relationship between humans, God and Satan.

They say the letter is rambling and not entirely consistent and understandable. This supports the theory held by modern scientists that - rather than being 'possessed by the devil' - Sister Maria suffered from schizophrenia or bipolar disorder.

It describes God, Jesus and the Holy Spirit as 'dead weights', and says 'God thinks he can free mortals'.

It also says God was invented by man, adding that 'this system works for no one'.

Another sentence reads: 'Perhaps now, Styx is certain', referencing the River Styx that separates the Earth and the Underworld in Greek and Roman mythology.