Tom, Karen and Matt are finally back in (well, outside) a pub as they return for the next episode. They are exploring why does God/the Bible say some things are sin, and other things are good? Are there any reasons for these things, or is it just something God made up - or the writers of the Bible made up? Aren't most of these ideas out of date?
If you want to be clever, you could say they are exploring the origin of ethics.