In this Slate blog, Jesus and the Gospel—What Really Happened? - Three historians debate. By Larry Hurtado, John S. Kloppenborg, and Alan F. Segal
, Segal discusses a strange sounding criterion for deciding whether evidence of the existence of Jesus is actually historical:
"But the most important arrow in the scholarly quiver has been and remains "the criterion of dissimilarity." The criterion sets a high standard: For scholars to arrive at an undoubted fact about the life of Jesus, they must eliminate as possibly biased everything that is in the interest of the early church to tell us. Conversely, for a fact about Jesus to be deemed historical, it must not be in the interest of the church to report it. It must be, in effect, an embarrassment for the early church. Thus, the criterion of dissimilarity is sometimes called the criterion of embarrassment."
An example of the embarrassing evidence is that Jesus preached the end of the world, but it has not yet arrived. This "embarrassment" supplies support for the idea that Jesus actually did so preach.