A 1,500-year-old papyrus is believed to be the oldest christian charm and contains some of the earliest-known references to the Last Supper. 

The Greek amulet was found among thousands of unpublished historical documents kept in the The University of Manchester's John Rylands Library. The document could help researchers gain insight into christianity just 300 years after the Roman emperor Constantine converted to the religion.

The finding shows how Christians picked up the ancient Egyptian practice of wearing amulets for protection; christians wrote passages from Bible on papyrus instead of prayers to Egyptian and Greco-Roman gods. The recently-discovered paper was believed to have been written on the back of a receipt for a grain tax. 

"The amulet maker would have cut a piece of the receipt, written the charm on the other side and then he would have folded the papyrus to be kept in a locket or pendant. It is for this reason the tax receipt on the exterior was damaged and faded away," said Roberta Mazza, a Research Fellow of the recently established John Rylands Research Institute. 

The document had been at the library since about 1901, but its significance had not been realized until now. 

"This is an important and unexpected discovery as it's one of the first recorded documents to use magic in the Christian context and the first charm ever found to refer to the Eucharist - the last supper - as the manna of the Old Testament. The text of the amulet is an original combination of biblical passages including Psalm 78:23-24 and Matthew 26:28-30 among others,"  Mazza said.

The researchers do not know who owned the charm, but believe it could have belonged to a resident of the village nearby Hermoupolis, making it an example of the Bible being significant to people other than priests. 

"It's doubly fascinating because the amulet maker clearly knew the Bible, but made lots of mistakes: some words are misspelled and others are in the wrong order. This suggests that he was writing by heart rather than copying it," Mazza said. "It's quite exciting.  Thanks to this discovery, we now think that the knowledge of the Bible was more embedded in sixth century AD Egypt than we previously realized."