What evidence, if any, exists to support the idea that Jesus had brothers and sisters?
Mark 6:3 names four brothers of Jesus, and mentions sisters as well. Plus, the Christian community in Jerusalem was led by James, the brother of Jesus. Centuries later, the doctrine of the perpetual virginity of Mary led to the denial that these were biological brothers and sisters. But the normal meanings of the Greek words indicate they were (and John Meier, a moderate Roman Catholic Jesus and gospel scholar, affirms the same thing, in spite of traditional Catholic teaching to the contrary). One further point: if one sees the birth stories as symbolic or metaphorical narratives (as the majority of mainline scholars do) and not as straightforward historical reports, then there is no reason to think Jesus was the first-born; he could have been anywhere in the sequence of children born to Mary and Joseph, even the youngest.
What do you think of the Gospel of Thomas? How often do biblical scholars use it, and for what reasons?
Scholars disagree about whether Thomas (discovered in 1945 in Egypt) is independent of or dependent upon the gospels of Matthew, Mark, and Luke. If independent (as probably a slight majority of scholars in North America would say), then Thomas may contain some early material going back to the time of Jesus that is not found in the New Testament gospels. Thomas contains 114 sayings attributed to Jesus--some of them quite similar to those found in the gospels, some of them very different. Of the latter, only about four or five are seriously considered as going back to Jesus.
What is your vision for the action that would come out of your scholarship?
The historical study of Jesus and Christian origins leads to the realization that the gospels are a combination of history and metaphor. Thus, this approach leads to a non-literal way of being Christian. It also leads to a way of being Christian that is both religious and political, both social and spiritual, just as "the Kingdom of God" in the teaching of Jesus was both religious and political.
Are you a Christian?
I am a deeply committed Christian, even though I don't think the gospels are "completely factual." For me, metaphorical narratives (such as the stories of Jesus' birth, walking on water, multiplying loaves, the wedding at Cana and changing water into wine) can be powerfully true, even though I don't think they are historically factual.
The identification of truth with factuality is a product of the modern period of Western history, and this is unfortunate. To use a phrase from the religion scholar Huston Smith, we have become "fact fundamentalists." People tend to think that if something isn't factual, it isn't true.
I think both biblical literalists and most modern atheists are "fact fundamentalists." The former insist that everything in the Bible must be factual if it it is to be true at all; the latter say that because some things in the Bible clearly aren't factual, then the Bible isn't worth much. I reject both options. I take the Bible very seriously as ancient Israel's and the early Christian movement's stories of their relationship with God.
One more important comment: if by "faith" one means, "believing," I don't think being a Christian has very much at all to do with believing. This is another modern development: only after the leaders of the Enlightenment began to call traditional Christian teachings into question did Christians start talking about faith as "believing doubtful things to be true."
I think being a Christian is about a relationship with God as pointed to by the Bible and Jesus. But I don't think it's about "believing in the Bible;" it's about seeing the Bible as a lens through which we see God, and entering into a relationship with the God whom we see through the Bible. I don't even think it's about "believing" in Jesus--rather, it's about a relationship with the God to whom Jesus points us.
So I don't want to choose between faith and fact. For me, faith is about our relationship to God, not about believing a particular set of claims to be true.
One last comment about faith as believing things to be true: somebody may choose to believe that Jesus was really born of a virgin or really walked on water. But believing it to be true has nothing to do with whether or not it is true; he was either born of a virgin or he wasn't, and what I believe about that can't make it one way or the other. You can't make something true by believing it to be true.
Believing is overrated. You can believe all the right things and still be untransformed, still be in bondage, still be miserable. Faith as belief is quite impotent. But faith as a relationship with God is transforming.