Enslaved people wrote the Bible, carried the messages of the apostles and spread the word of Jesus around the Roman empire, according to a shocking new book by the theology professor Candida Moss. God’s Ghostwriters: Enslaved Christians and the Making of the Bible argues that apostles and early Christians used enslaved scribes, secretaries and messengers to write the New Testament and shape the very foundations of Christianity.

“The overwhelming literary and archeological evidence shows that this kind of work was done by enslaved or formerly enslaved people,” says Moss, the Edward Cadbury professor of theology at the University of Birmingham. Scholars think only about 5-10% of Romans were literate: the very wealthy – and the people they enslaved.

“One reason that slaves were educated to do this work is because – especially when it comes to something like copying out a manuscript by hand – it hurts. So wealthy people who were educated didn’t want to do it”, Moss says. “And, particularly as their vision got worse as they got older, they needed enslaved people to do this work for them, because they couldn’t do it themselves.”

She says that even “freedmen” – formerly enslaved people – who undertook these tasks were often not what we would now consider to be “free”. While allowed to earn money for themselves, they were usually obliged to give a portion of their wages to their enslavers, live in their households and acquiesce to sexual favours.

The first followers of Jesus and the early “authors” of the Bible were not well educated and so could not write themselves. “So, like other groups, they pooled their resources and rented scribes and copyists to write the stories and letters that we know as the New Testament”, Moss says. Other early Christian writers, including the author of the Gospel of John and Ignatius of Antioch, were elderly men who would have struggled to read and write without glasses.

Among the apostles, only Paul was literate. “And he tells us he used other people to read and write”, whose names suggest they were enslaved, says Moss. One example is Epaphroditus, letter carrier of Philippians who also supported Paul while he was imprisoned. “[The name] Epaphroditus was especially common among enslaved and freedmen because it is related to the goddess Aphrodite and means ‘charming’ or ‘attractive’”, Moss says.

It is a male name which carried sexual overtones at a time when young boys were sexually exploited. “To call your child Epaphroditus if your child was not enslaved would be like calling an English child Jean-Luc Baptiste and expecting people to think the child wasn’t French,” says Moss.

Tertius, another common name for an enslaved person, openly declares he wrote a letter to the Romans for Paul. “Tertius writes: ‘I, Tertius, wrote this letter’”, Moss says. “The letter is arguably the most important text in the New Testament. It is the foundation for Protestantism, and Paul is obviously involved. But he wrote it with Tertius. So the question is: why aren’t we remembering Tertius? And what has Tertius contributed to this letter?”

Moss wants to shine a spotlight on the contributions she thinks Tertius, Epaphroditus and other enslaved workers made to the Bible and the rise of Christianity. “The writing, the editing, the copying, the movement of those early Christian texts – what you might call ‘missionary activity’ – all of that’s being done by enslaved workers.”

The first interpreters of Christian scripture were the couriers who carried and performed the texts of the New Testament around the Mediterranean – and they were enslaved, says Moss. “When those texts are read aloud to largely illiterate audiences of Christians and potential Christian converts, it’s enslaved people doing that important work”, she says. The way that these couriers interpreted and spoke the words they were reading mattered, Moss believes, as they were “the faces of the gospel to those audiences”.

Yet Moss thinks ancient people saw enslaved workers as “mouthpieces” or “mindless vessels” who had no authorial impact on the texts they were writing and interpreting for their enslavers. “Christians bought in to the idea that enslaved people just did the will of their ‘masters’”, she says.

By contrast, Moss argues that enslaved people are likely to have contributed to the parts of the Bible which suggest that enslavers will be brutally punished in hell: “I think that’s enslaved people putting that into the text,” she says. “You can see it as an enslaved revenge fantasy. It’s not within the power of the enslaved people to change the entire social order, but you can see resistance here, the idea that in the future people will be rewarded, because they were oppressed.”

Some reviewers have criticised Moss’s book for using conjecture and speculating on the past, including Daniel Rey, who said in his Spectator review, that it takes an “unnecessary hectoring” tone, although he praised the book overall as “a massive achievement”.

Any reconstruction of the writing process of an ancient text is necessarily going to be speculative, and Moss admits she does not steer away from anachronism. At the beginning of God’s Ghostwriters, she explains that “disinterested history is sometimes also morally negligent”. But, while there are certainly elements of modern interpretation to her reasoning, the author is certain that her “basic argument that enslaved people contributed to and co-authored and made the Christian Bible is not speculation. Those facts aren’t up for debate.”

God’s Ghostwriters by Candida Moss (HarperCollins Publishers, £25). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.

• The main image on this article was replaced on 2 April 2024 to use one showing the New Testament.