If there were an historical Jesus, it really wouldn't matter so much what he taught because he'd have had so little control over what his followers did with his message. That message would have been degraded, co-opted, and censored by the many factions that seem to have emerged within just a century after his death.

Jesus might also have been a radical, apocalyptic Jew who helped inspired Jews to revolt against Rome. We'd never know because such a message would have been written out of the record, given how the wars played out.

What matters historically, I think, is the Jesus character who's the protagonist in the New Testament. The historical Jesus is unknowable and had little direct impact on the Church that arose in his name.

It's Eisenman who finds parallels between Christianity and the Dead Sea Scrolls, right?