"Pantera is from Palestine. And he dates 62 years old when he dies ... He's on the frontier in Germany. And if you figure his date and where he was ... he's a teenager. You know, a young man maybe 19 or 20 at the time Mary becomes pregnant," Tabor said.
The suggestion that Pantera may have been the father of Jesus has been proposed before, however.
"It's not some new discovery," said Dr. Donald Carson, an expert in New Testament history from Trinity University in Illinois. "It's presented in the book as this great find that has been suppressed ... But it's been discussed and carefully weighed by centuries of scholars. There is nothing new here except the association of names that go back, at the end of the day, to reports of the enemies of Christianity from the second century. Pantera was an incredibly popular name at the time of Christ."
Carson argues that Tabor's views are shaped by his own materialistic philosophy, which does not allow for any supernatural or extraordinary elements -- such as a Virgin Birth.
"What Dr. Tabor has done is assumed that the whole thing cannot be," Carson said. "It is a sham and therefore the evidence has to be jiggered, it has to be selectively appealed to in order to take away the evidence of God actually doing something in space, time, history. At that point, no amount of evidence will ever convince him unless he's open to the possibility that Dr. Tabor himself is wrong ... and that God has disclosed himself in space, time and history through a man. Namely, Jesus of Nazareth."
If Tabor's book is controversial on the birth of Jesus, it also raises questions about Jesus' early ministry. Tabor suggests there were two messiahs, not one.
Tabor took "Nightline" to a second cave on our visit to Jerusalem -- this time to the East.
The Suba Cave, as it is now known, is the site of a major archaeological dig. Inside the cave are primitive, centuries-old etchings, which Tabor believes depict the life of John the Baptist. The cave also contains thousands of first-century pottery shards.
Tabor suggests that given the number of individuals, who may have been baptized in Suba, it's likely that Jesus, not John, was actually performing the baptisms.
"I like to surprise with my answers," said Tabor. "Are you ready for this? This is John's area but you know text-wise, we have no record of John baptizing here near Ein Kerem and Suba. He's up along the Jordan River in the Jordanian wilderness. The person we have a record of baptizing here is Jesus, Jesus the Baptist."
Tabor believes that, contrary to the New Testament, Jesus and John the Baptist were twin Messiahs. He says that early texts anticipated more than one Messiah and that the practice of baptism suggests that they were acting similarly in their respective ministries.
"It hit me, how this would have electrified the country," Tabor said. "You see, all these predictions of two Messiahs, and we've got two Messiahs on the ground, operating, one in the north -- John the priest -- one in the south -- Jesus the king. And they're baptizing thousands of people."