Both and Neither

Interesting article in the Times about a Christian seminary and Hebrew College essentially sharing a campus, at least until this line:

[Dr. Mobley -- Hebrew teacher] now teaches a course on the story of Isaac in the Jewish and Christian traditions with Rabbi Or Rose. On a recent Thursday night, students sat in Hevrutah, a Jewish method of discussing text in small groups, and analyzed the practice of child sacrifice in ancient Hebrew tradition and others.
It was, in fact, a thread that ran through a number of Biblical passages, Dr. Mobley said.
"Given some of the dark origins of Jewish and Christian practices," he said, "how does that make us feel about where our traditions came from? Do we prefer to keep the cellar door locked, or do we occasionally reopen it and examine?"

I'm not quite sure what he's talking about, or why interfaith dialog helps figure it out.