The ethics of talking politics or religion at work include one word: respect. Golden rule: "Just because we have a right to do something doesn't mean that it is right to do it."
With very few exceptions, we shouldn't discuss politics and religion in the workplace. These discussions have nothing to do with our job and can only interfere with it. Beside, engaging in such conversations might be interfering with the ability to carry out duties and meet the needs of customers and company alike.