You can find his sermon here.
A couple of quotes from his wonderful sermon:
A wonderful teacher and writer named William Willimon urges us to allow the Bible to challenge us every time we read it. Following Jesus is a dynamic experience and encounters with his memory and his Spirit should never leave us the same as we always were.
Another way of looking at difficult passages like this one is to remember that the authors of scripture did not always intend give us answers but sometimes wanted to pose questions so we could wrestle with them. There is ample evidence that Jesus did that. The asking of unanswerable questions has always been an effective teaching tool for religious leaders of all traditions.