As an atheist who has plenty of non-atheist friends, as I'm sure most of us do, I find there's something that comes up occasionaly and that I've found myself mulling over recently: Isn't it impolite to expect me to participate in "saying grace" when I'm at your house for dinner? Isn't it especially bad to give me the "honour" of leading the dinner prayer?
Now, I'm generally a believer in the "When in Rome...." approach, and am happy to do things I consider harmless in order to fit into someone else's culture. If I'm at your house, accepting your hospitality, I expect to accept your customs for it too. And so in the instant, I don't actively object to the practice. If I'm asked to "lead", I politely decline, and after one or two, "No, really, I'd rather not," statements it all moves on with no residual awkwardness. And as a participant, I just sit quietly while the others do their thing. I wouldn't disrupt dinner and offend my hosts by making a scene about it all.
But as an exercise in thinking about it afterward, I've found it interesting. I like to turn these sorts of things around, and see what others would think if the tables were turned.
Suppose I had a custom of saying an "atheist prayer", thanking the land and the sun and the farmers for the bounty, and expressing belief that God is a myth. Would my Christian friends who say their preprandial prayers willingly join in mine? If I were a Wiccan, a Druid, or a Satanist, could I expect those with more common religious beliefs to go along with my dinner invocations?
This relates to the broader area of accomodating each other's food preferences and requirements. Most people would avoid serving ham if an observant Jew were invited, but perhaps they wouldn't know to avoid shrimp, or not to serve creamed spinach or buttered carrots with the kosher steak. Vegetarians can usually make do, and some will even go ahead and eat meat at occasions when it would be awkward to decline it. People with food allergies are used to dealing with them, and hosts are certainly understanding when one tells of gastric stress associated with an intolerance for cheese, or anaphylaxis brought on by nuts.
But we don't give the same consideration to those verbal expressions. "It's just a prayer," we say, "How can it hurt?" And, of course, it doesn't "hurt" in the sense that food reactions do. But one can feel just as "dirty" after participating in a prayer that one disagrees with as one can after eating "unclean" food. Expecting someone to go along with prayers to a deity he doesn't believe in is a spiritual violation. I've heard people wonder, "What's the big deal? Just do it to make them happy." Well, and that's what I do, indeed, but why not say instead, "What's the big deal? Forgo the prayer tonight, out of respect for our atheist guest."? Diners can give silent, private thanks, as they desire.
Or, better still, why not have a secular statement of thanks to use on occasions when "prayer" isn't appropriate? I think few would object to having the host say something like, "We are so grateful for the opportunity to sit down with good friends to a bountiful meal. Enjoy!"