What an interesting topic!
We just recently started going to a UU church and I NIP my 5 mo old with no problems. DH and I had a laugh, b/c as my DS was trying to latch on, he made some LOUD slurping noises, and this was during a very quiet time of the service. To think that the smallest person in the entire room was making the loudest noises while eating, lol. BTW, I don't eat during church, but if my toddler needed a small snack, like a cracker or pretzel to keep him occupied during service (usually they have childcare, so this isn't an issue), I would have no problems giving it to him. I'd just make sure that if he dropped any crumbs or anything to pick up after ourselves.
I have a cute story to share. Yesterday, a lady (about 70 yrs old+) came up to me before service, b/c I was wearing my son in a mei tai carrier. She told me about how she had one too and how she liked that it could be used front or back carry! I thought that was cool! Then she asked, "you BF your babies, right?" I said, "yes." She said, "oh, I can tell if they are BF babies, their skin look so much better than FF babies' skin." I had never heard that before, so I asked her what she thought FF babies' skin looked like and she said, "the pillsbury dough boy." Lol, I just kind of laughed. I will have to look harder next time to see if there really is a difference (problem is, I only hang out with BFers, so I don't see too many FF babies up close). Even cooler yet, is that this woman told me she nursed her kids until she they were 3 yrs old, and I'm not talking a woman, "from the old country" or anything like that. Then, after service, one of the members that is very involved in the church came up to me and told me that when his mother passed away, they did not know what to do with her rocking chair. So, they donated it to the church, and it sits in the back of the room (I had not noticed, b/c we usually get there w/ little time to mingle) and I should feel welcome to use it as I needed to. I thought it was very sweet of him to let me know that there was a rocking chair for a BFing mom to use, instead of having to try to BF sitting in the pew. They are all smitten with my toddler and baby, b/c the congregation is made up of mostly 60+ year old members.
Now, my DH is originally catholic and I have never been comfortable in a catholic church, whehter I was BFing or not. I have never had to BF at a catholic church before, but if I did, I would probably make sure I sat close the back of the church. At the UU church, it is so tiny (only 50 something members), that you just sit wherever you can find a seat... it's THAT small, lol.
As for BFing a toddler in public, I BF'd my 15 mo old during my pregnancy and was prepared for ppl to give me a hard time, but nobody ever did. Unfortunately, my toddler weaned right around that time, b/c my milk dried up. With my youngest DS, I plan to BF until he weans on his own. I think my problem with BFing a toddler in public has more with my own concerns than with what other ppl think. I don't know about you, but by the time my babies are 4 mo old it is VERY difficult to get them to concentrate when it's time to nurse. They are so easily distracted, I always prefer to go somewhere darker and quieter to nurse, just for my own sanity. Otherwise, the baby is popping on and off and whipping his head this way and that with my nipple still in his mouth! OUCH!
I did explain to her that I was fine with staying where I was, but the baby was shy about it. 
