I agree with you. It might be time to let your family know how you feel.
It might also be time to make alternate plans for your mother's birthday.
Let your family do their religious thing, and you can take her out, just the
two of you, at another time.
Don't be forced to participate in what you don't believe in.

I flatly told my very Christian mother that I wasn't going back to church. See I'd been away for about a decade. Then had a breakdown and fell back on my old ways, attending church again. Once the breakdown was over I stopped going. She noticed. Asked when I was coming back. I told her I wasn't. She's barely spoken to me since and I'm only one of her two children.
Beyond that I started putting up agnostic an nd atheist posts on my fb page. I'm sure I'm on the "prayer chain".
My ways aren't accepted. They just look at me as being lost. Like the prodigal son. It will probably remain that way until everyone passes.
As far as your mom, I'll encourage you to go just to show her you love her. Even if you need to "accidentally" show up after service

Go for your mom, and don't worry about the rest of them...
If it gets uncomfortable, just Do a fade and disappear...
After eating some cake, of course...

When I was around nine, I told my mom I didn't think God was real. She quickly convinced me that it was better to believe and be wrong than to not believe and be wrong. I told her a couple years ago. You know I have struggled with my faith when I was young. I have come to the point that I can't make myself believe anymore. I am done trying to believe in something I don't. You tried to teach me. I am sorry but I just can't do it anymore. I don't believe. She didn't say a whole bunch just said that she believes and would always believe. It made her sad. I told her that I respected that was how she felt. I never objected to my family praying at family events afterwards. I respectfully let them do their thing and did not participate in that part of the event. However, some of them did disown us. When my son came out as transgender male a couple years later, mom still loves us unconditionally though just like we love her unconditionally. Don't know if this helps but I thought I would share my experience.

I am shunned by my family. Ah, well.

I agree with the people who say go for your mother, and also for your family. Unless the people act out in disrespectful ways toward you, there shouldn’t be any harm in being there physically. I attended church with my ex-wife very regularly for 17 years. I looked at it as basically a case study on the low end of my experience (as if I was doing a sociology experiment)...and as a half-hearted attempt to find some level of belief I’d had in my teens; before I realized the feelings and the logic just weren’t there. Staying away from the event could make what’s supposed to be a special day for your mother into something about you. When I went to church with ex, I just wouldn’t sing along or pray or participate in most of the stuff I considered to be sort of ridiculous. I did take communion, mostly because if I didn’t I would have blown my cover. And I had to keep a cover on my lack of belief. My ex-wife turned out to be very conservatively christian...an element of herself she kept concealed for about the first three years we were married. I went through the motions with her mostly because I loved my kids so much. Family is worth a little bit of charade and play-acting.

Go for your mom. As someone who recently lost mine, take every opportunity that you have to spend time with her. Telling her now in her old age will only put some stress in her life. I never told my mother, my brothers knows and they never told her. Do it for your mom. Go and spend the time with your mom, she will appreciate it and you will cherish that time forever.

I never outright came out. I just kept dropping hints and started asking questions they couldn't answer and they figured it out. They still hate me more for it, but they can keep their love and spend it on my brother

I honestly never exclusively came out to my family or friends. Most of them know or at least have an idea that I am atheist just by the way I talk about religious subjects when they come up. I don't go out of my way to be an ass or to cause a confrontation but I'm not afraid to voice what I have to say when asked.
Good luck in letting your family know!

If your family doesn't already know, your mother's 87 birthday is probably not the best time and place to make this announcement. You don't want to ruin her day.

She's asking for suggestions, so support a non-religious location, but if more want the service then, one day won't kill you. And it's for your mom. Imo

"All thoughts & opinions are welcome". 'Ya think? The church has been a source of security for our African American citizens for decades, just as the bar scene was/is for our gay citizens. It seems to be so engrained in the culture that only time & progress can/will unfetter them from this bond. It has caused me much consternation with co-workers of extreme "faith" who have targeted me due to my apostate views. I forgive them as I get their compromised intellect & need for religon. But they, as the christ followers, do not forgive me as commanded & can not see their way to do so, I avoid them. It does weigh heavy sometimes as I participated in the civil rights movement & have seen them bond with bigots only because the bigots were believers.

It’s just obvious that I’m not religious through Facebook or whatever. My brother told me that our mom told him that she didn’t think I was xtian, to which he replied that neither was he.

I honestly didn't know "coming out" as non-religeous was a thing until I joined this site. I certainly understand that there can be huge ramifications from revealing your true feelings to family or friends. I had just never thought about it before. I can't remember when I came out as atheist. I'm sure it was rather nonchalont and matter of fact when I did.

You could always interrupt the service mid-way to make your announcement if you really wanted your point to sink in. Lol.

Not sure this would be the best venue to make your beliefs known to your mom. Set aside some personal time to give her the news remembering this could be a big deal with her as well. Give her the respect she deserves on her birthday, it is your mom. You don't have to participate in all of the ceremonies or sermons if that makes you uncomfortable.

As others here have said, this is probably not the best event to use as a platform to "out" yourself. You could submit feedback suggesting a more secular location for the event. This would drop a fairly big hint. On the other hand, if you think this (a church service on her bd) is something she would really love, maybe it's best to just go with the flow this time and choose another time and place to come out. To me, mom's perspective is the most important one in this situation. Hope this helps.

I couldn't stand being around my family, so left after HS. I'd been abused as a child by stepfathers, so had a love hate pity relationship with my mother. She chose, one at a time, five loosers as a husband. Thus, I was under no pressure to tell them about my beliefs. After she died, I told them. We don't communicate. They live their delusion, going to church several times a week, I imagine. I am happier without them around to preach.

I was 12 when I came out as atheist. My family didn’t take it to well. They thought it was a rebellious phase of it is has lasted 35 years so far. They get over it. My best advice is just be honest. I still go to My families church when ever my nieces or nephews are in a program. Just to support them. But I don’t hide my atheism from anyone in the church. They even accept me in my brother’s Mormon church.

Shelton, I think I understand how you feel. Tired of playing along, but also wanting to be accepted and respected for who you are?
I'm leaning towards the "Do it out of love for your mother" responses. What I wouldn't give to be celebrating my mom's birthday with her now.
The good news is that there no wrong answer. Just what works for you.

I suppose it would be a bad idea to just go along with it all, but then sign her birthday card, "from your agnostic/atheist son."

I never "came out" & make it very clear that my beliefs & my "relationship with god" (insert sigh & eye roll) are my own & no one else's business. When asked why I don't attend church, I say "sorry, I was busy practicing witchcraft & becoming a lesbian" then laugh at their shocked expression & say, "not really, I just choose not to be like the pharisees & sadducees" & keep it moving.

Try to get an itinerary & skip the service (had to see a man about a dog) & show up for the food. Be sure to have a list of topics to switch to when bible stuff comes up...like, "speaking of Jesus, when do you think the christian congressfolk in DC are going to start taking care of the poor, like jesus did? Think they will pass those christian bills to provide free healthcare to the sick & needy, like jesus did? Think they will at least take care of the little children? Pretty sure jesus didnt mean for the nation to neglect kids till they died as a way to let the come unto" Jesus."

(Or maybe not. I'm not invited to family things anymore so my sarcastically honest ass is not the best example.)

Offer the idea of arestaurant-if not do something on your own. I don't get invited to my family's celebrations anymore. They are more religious than I was raised and they know I won't go.

Why not reply "How about that potluck dinner!". (Or name a restaurant).

That poor woman has lived this long she should not have to sit through a service on her birthday!

I agree that you should let your family know -- you should be able to be who you are around them. But what would your mother like? It is her birthday, after all. I bit my tongue through some church services during my mother's last years, and though I certainly didn't enjoy it, I also don't regret it. My support and companionship meant a lot to her.

I already kind of knew which family members were narrow minded so i took a nuanced approach and spoke to each of them individually. I suggest you talk to the ones first who prescribe to a pecking order. The general language that I used kind of established equivalence and respect with everyone. Specifically I said "I don't believe in a Christian god because i see no evidence and i am an evidence based thinker. But as an Agnostic i'm not ruling out that science will discover evidence of intelligent design in the universe sometime in the future. Because of that i respect your right to have faith in your ideas. I will always love you and i hope you will still love and respect me for who i am and what I think." That was my template. I nuanced it based on who I was talking to. I participate in their rituals with effusive kindness and tolerance to show them religion is not the source of all things that are good. Best of luck with your family. I humbly hope this comment helped.