Comparing where the candidates stand on religion.

[Tiberius]

No, but he certainly sounds like one, sometimes. The fact that he invited douchebag Grover Norquist onto 'Bullshit' as the reasonable voice speaks volumes to me.

Do you understand what a Libertarian is? If not, very (very) basically:

Social issues: Liberal.
Economic issues: Conservative.

However, one is incorrect to say that Libertarian = Conservative or Libertarian = Liberal (unless you are talking about classical liberalism). It is incorrect to say Libertarian = Republican as well. Libertarians have their own political party for a reason.

This said, it doesn't surprise me that they invited a conservative economist to support their show.

Edit: Having read through Mr Norquist's Wikipedia profile a bit more, I can see that he espouses numerous Libertarian ideas as well, so yes, it's not surprising at all that they invited him.