My aunt’s family does that. Your instinct is correct.
While i totally agree with you, but a personal suggestion, if you want to make things work with your spouse, you got to do what your in laws tell you.
Almost none of what you say bears any.particular relevance to my point. It’s nothing to do with who controls the scene, it’s just that everyone, guest or host, should make a little effort to keep things friendly and comfortable, IMO, otherwise the point of the event is something other than to welcome and entertain, or to enter in and be gracious.
I haven’t a clue what the Fox News reference was about, but you missed the point - which was merely to illustrate asymmetry, not to argue equivalency between prayer and nose picking. Sorry if this wasn’t as obvious as I hoped it would be. Let’s try again;
[certain activities], when performed, make others present feel awkward, threatened or uncomfortable in any of a dozen different ways. Assuming they are aware of this, a polite host will try to make adjustments for the comfort of the guests, and assuming they are aware, a gracious guest will behave in a way that does not embarrass the host or other guests.
What, slipping out the door with a quick “no thanks”? I’d hate to think what you’d call what I think of as a “big production” - which would involve at least loudly announcing to the room that you “don’t go in for all that superstitious crap”.
That’s not getting “all worked up”.
“All worked up” is what you get if you invite me to your daughter’s post-clitorectomy celebration (that’s happened!) Police were involved.
If you now they always do the hand-holding stuff, make sure that you are seated next to a hottest, sexiest person at the table! Get some good out of that hand-holding.
I think you’re judging them too harshly. They have a ‘ritual’ performed to their God at mealtimes. I think that they believe it would be disrespectful to Him to cast it aside, since, if they are Christian, their first loyalty/love should be God.
So, it isn’t rude, IMHO. Part of the problem of manners, per se, is that there are no *firm *rules. I’m sure they would allow you to perform your rituals in your own home, as host, and not consider you rude.
There may, however, be a breakdown in communication (among the mortals).
hh
Mom & I were guests of friends at Thanksgiving. We’ve never actually discussed religion tho they know Mom & I are religious & politically conservative while we know they are politically moderate-conservative but not how religious. They did not mention saying Grace before the meal. Now, Mom & I both feel awkward not doing that at Thanksgiving or Christmas but we both did it in our heads & went on. If they had been our guests, Mom or I would have said Grace & they would have been perfectly civil about it, no matter what they believe, because they are kind & considerate people. (And great cooks!)
Is that really so difficult for people?
When I invite you my house, I invite you to part of my household for the evening. I ask you to share what we have and do. How a person would force someone to pray is a mystery, but being respectful of your hosts seems like a nice thing to do.
I don’t believe in Santa, but if a five year old asks me about him, I always play along. Especially in their house.
I’m okay with that.
Well, one way is to put the victim on the spot in front of the other guests by demanding that he lead the prayer. My father does that to me, because he thinks atheists are as imaginary as Kris Kringle and that if he can just get me to mouth the words enough times, I’ll get right with Jesus.
Sure, it’s incumbent on the host to be respectful of his guests as well.
When my in-laws were alive, and I had dinner at their house, they said grace. I didn’t, but was respectfully quiet–to me, it was “their house and their rules”. I didn’t expect them to not say grace simply because I was a guest and a non-believer.
OTOH, when they came to my house for dinner, and we didn’t say grace, they accepted my rules, and didn’t push me. My house, my rules. It worked for us that way.
Do you warn me about that? 
Ok, I agree that is something to get worked up over. That actually happened to your daughter? And there was a party? Do you live in tribal Africa?
I’m somewhere between Agnostic and Atheist on the religiosity scale. If I’m eating with a group who likes the saying grace before meals, with or without hand-holding, I do enough to not stand out or make anyone else feel uncomfortable. I will hold hands (if asked of me) and stare at my plate, generally.
I figure it’s 30 seconds of boredom for me, and it makes everyone else happy so why not? They all know I’m essentially a heathen, and if anyone actually looked at me they’d know I wasn’t really taking part. But I see no reason to diss something I don’t understand or enjoy when it isn’t doing me or anyone else any harm, and may be giving some people some pleasure.
You don’t bow your head, you bow from the waist. In any case when I went I didn’t bow for anyone - it was a mutual greeting. If God bowed his head to me at the same time it would be okay.
Why would believers want non-believers to pretend to pray? Doesn’t it make sense that the non-believer should remove himself from the ritual that he clearly does not believe in?
That would be respecting the fact that other points of view exist and should be respected.
I don’t think it’s so much pretending to pray as it is being part of a group and sharing a moment - spiritual for some, reflective for others, or possibly just habit all around.
To my way of thinking it’s just not worth the mental effort to get irritated over it, never mind up in arms. And no, I’m not going to leave the table or come late to the table to save myself 30 seconds of staring into space, let alone to prove a point. Again, the ritual isn’t hurting my feelings or making me truly uncomfortable, why should I make multiple others uncomfortable or unhappy?
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Or, yeah, what Czarcasm said much more clearly and succinctly 
Were they invited, or did they gate-crash?
I don’t see anything wrong with sitting quietly while others pray. And holding hands doesn’t particularly bother me, but I could see some people finding this a little too personal and participatory.
On a side note, whenever sitting down to eat a meal prepared by my mother, we all prayed for our continued good health. Didn’t always work.