Writing in the new issue of Biblical Archaeology Review, Andre Lemaire of France's Practical School of Higher Studies says it's "very probable" that an inscription on a burial box for bones refers to Jesus of Nazareth and was written around A.D. 63.
The inscription reads, "James, son of Joseph, brother of Jesus." That would fit the New Testament account that Jesus had a brother named James, and the tradition that James was the son of Joseph, the husband of Jesus' mother Mary.
"Sometimes [there's a] mention of the father, very rare to have the mention of the brother," Lemaire — unless the brother was famous.
Some biblical scholars describe James as Jesus' half brothers, others say he was a cousin, reports CBS News Correspondent Randall Pinkston, but there is widespread agreement that he led the early church in Jerusalem and was executed in A.D. 64. The age of the box would place it in the same time period as that James.
"It's very clear that it dates from the First Century, before the destruction of Jerusalem," said Lemaire.
The sensational claim, if true, could become one of the great archaeological discoveries in modern times.
"In all likelihood, I think what we have here is the first and the only archaeological attestation of Jesus of Nazareth," Biblical Archeology Review's Herschel Shanks told CBS News.
But there's this major question: Did this box name Jesus of Nazareth or some other Jesus? After all, that name was common in the first century, as were James and Joseph.
"I think it's a wonderful discovery and shows that even though we think we know everything about the Holy Land, there's still a lot of new things to be found," Father Jerome Murphy O'Connor, a New Testament archaeologist, told CBS News Correspondent Robert Berger.
However, until more scholars see the inscription for themselves, the jury is still out.
"You have to see the original, otherwise no serious scholar will make a judgment.
"We need to see the object. I mean it's actually so intriguing and the basis seems so good that we would want to see the object just to confirm that it is authentic, not because we think it's inauthentic."
Lemaire pins his circumstantial case on the unusual naming of both the father and brother on a burial box, known as an ossuary. There's only one other known example with three names, so he figures something about the brother must have stood out. Jesus would certainly qualify.
However, archaeologist Kyle McCarter of Johns Hopkins University noted at a news conference Monday that the brother might have been named because he conducted the burial or owned the tomb.
Under Christian teaching that would rule out Jesus of Nazareth, who rose from the grave and ascended into heaven decades before James was stoned to death as a Jewish heretic in A.D. 62.
Two poles of reaction quickly emerged Monday.
Rev. Ben Witherington III of Asbury Theological Seminary in Wilmore, Ky., another news conference speaker, sided fully with Lemaire's claim. He's a conservative evangelical who takes the New Testament as reliable history.
But Robert Eisenman of California State University, Long Beach, attacked Lemaire's claim, calling it "too perfect." He figures some "extremely clever" forger must have produced the box. That fits Eisenman's skeptical belief that the New Testament is highly fictional. He even thinks "Jesus' existence is a very shaky thing" — something few other scholars would agree with.
Whether Jesus of Nazareth is the person named, Lemaire and the archaeology magazine offered a detailed case against forgery.
The magazine said two Israeli government scientists did a microscopic examination of the artifact's inscription and surface patina. They concluded the box is ancient and there's no evidence of modern tampering.
Lemaire said the handwriting is clearly in the style of the first century A.D. and another specialist, the Rev. Joseph Fitzmyer of Catholic University of America, agrees. Moreover, Lemaire notes that ossuaries were only in use from 20 B.C. to A.D. 70, fixing the time frame.
Another issue: The owner required Lemaire to shield his identity, so the box's location was not revealed. Nor is anything known about its history over the past 19 centuries.
Biblical Archaeology Review editor Hershel Shanks said the owner bought the box about 15 years ago from an Arab antiquities dealer in Jerusalem who said it was unearthed south of the Mount of Olives. The owner never realized its potential importance until Lemaire examined it last spring.
"Something so startling, so earth-shattering, raises questions about its authenticity," Shanks acknowledged.
Lemaire, who was raised Roman Catholic, said his faith did not affect his judgment, since he studies inscriptions only "as a historian — that is, comparing them critically with other sources."
The archaeology magazine is negotiating to display the box in Toronto during a major convention of religion scholars in late November, and possibly in the United States.
James is depicted as Jesus' brother in the Gospels and head of the Jerusalem church in the Book of Acts and Paul's epistles.
Until now, the oldest surviving artifact that mentions Jesus is a fragment of chapter 18 in John's Gospel from a manuscript dated around A.D. 125. It was discovered in Egypt in 1920.
There are numerous surviving manuscripts of New Testament portions from later in that century. Jesus was mentioned by three pagan authors in Rome in the early second century and by the Jewish historian Josephus in the late first century.