He was also on 'Real Time with Bill Maher' the other night (I don't have HBO at home, but I was still on my road trip and watched in my hotel room in Minneapolis on Friday) but he didn't seem to be on his game, primarily I think because Bill was going off on one of his anti-religion rants and his last guest was Penn Jillette (of Penn & Teller fame) who just poured more fuel on Maher's flames.
Thom Hartmann is a person who seems to take his and other people's religious beliefs very seriously, but also thinks that while religion may provide a moral compass for many, it has also been used as justification for much of what is evil in the world, however he's not the type of person who accepts the idea that religion is a total fraud and that we would be better off if ALL religions were banned, as is the view of both Maher and Jillette, and I suspect that Thom was put off by this and avoided getting dragged into what I'm sure for him would have been a no-win situation. He did get a few good points in early while they were still dealing with political and social issues, but when it turned weird he looked a bit uncomfortable and quieted-up.