Experts are responding with a mixture of caution, hope, and skepticism to new claims that a recently discovered trove of 70 ancient sealed books may represent some of the earliest Christian documents.

Written on lead in Hebrew and Aramaic, the secretly coded books – or codices – were hidden for centuries in a remote Jordanian cave until a traveling Bedouin found them some five years ago, according to a statement released last week by British Egyptologist David Elkington. Depictions of crosses on the lead-bound leaves, coupled with metallurgical analysis, suggest to Mr. Elkington that these might be early Christian texts that pre-date even some letters in the New Testament.

Others aren’t so sure. All evidence to date suggests Christians didn’t use the cross as a symbol until the 4th century, according to Hershel Shanks, editor of Biblical Archaeology Review. The use of codices also dates to a later period, he said, and metal analysis has yielded no precise dating in this case.

“We have no fact about these that would indicate that they are Christian and date from this [mid-first century] period, except for some vague metallurgists who say they ‘could,’ ” Mr. Shanks says. “On the contrary, we have a number of things – the cross, the codex, [and other symbols] that counter this claim.”

New Testament scholar Craig Evans also hesitates to assume much about the early codices. They could be very significant, he said, if they really do trace to an early Jewish group that regarded Jesus as Messiah. That’s because most of what’s known about first-century communities comes either from Paul’s scriptural letters to Gentile churches, or from the Dead Sea Scrolls, which convey the traditional Jewish beliefs of first-century Essenes. Early Jewish Christians, as Evans calls those with Messianic beliefs, remain less well understood.

But “that’s a big if,” says Mr. Evans, a professor of New Testament at Acadia Divinity College in Wolfville, Nova Scotia. At this point, little is known about the content, purpose, or date of the codices. He says he’s hopeful that they’ll shed fresh light on Christian origins, but he’s not confident they will.

“To make claims right now about these being really early – ‘middle of the first century,’ or ‘earliest Christian writings’ – that’s a bit reckless,” Evans says.

Several factors are keeping the codices cloaked in mystery, at least for now. The fact that they’re written in code means scholars will need to crack the code before deciphering what’s said on the lead pages. And getting access to the texts could be difficult.

They’re reportedly in the possession of an Israeli Bedouin who claims they’ve been in his family for more than 100 years. Elkington’s team disputes that story, alleging instead that the codices were illegally smuggled out of Jordan after their recent discovery in a cave.

The Kingdom of Jordan is reportedly working to recover the codices under a law that gives the state ownership of newly discovered antiquities. Meanwhile, Elkington has announced that a book and documentary film are in the works.

“There is likely to be considerable academic and political debate about the collection’s authenticity, meaning, and interpretation,” said a March 22 news release from David and Jennifer Elkington. “But now there is also a race against time to safeguard the collection’s future.”