He talks about the birth of the word "Christian" in politics which is quite fascinating. It's a bit of a history lesson. I'm not atheist myself though I was for many years so I can relate very well. I now self-describe as panentheist if I'm forced to describe myself in one word, which is unfortunately often necessary for succinctness. That said, I am very impressed by Penn's objectivity and ability to speak about a subject rationally. He also talks about what politicians say about their beliefs vs. what they actually believe and some other things. It's a long video but a good watch.
Note to mods: I may not have picked the best section. I won't be offended if this gets moved to a section you consider more appropriate.