Bengt Lemne from Gamereactor has interviewed Ed Beach the gameplay designer of Firaxis for the Civilization 5 addon Gods and Kings. They were talking about religion, diplomacy, and combat in Civ5:G&K. Here is the video of the interview and a transcript, which has been edited for style and clarity:
Gods and Kings, I just got a demo, and I thougfht it is similar to the press release about it: A new expansion, they are writing about religion for Civ5. For me it's not a huge deal, because I played religion in Civ4. But vow, when I saw the demo, that's gonna change the game as I play it, completely.