I've had this theory in mind since forever but I've been scared to talk about it bc it's so niche and people probably won't care but I do so HERE WE GO :
I'm 99% sure there used to be good weavers in pharloom, that they were killed because they were too nice to leave space for a more tyrannic rule, and that they're the weavers we see on the effigies in-game.
First we have Camora, the "weaver of the path"
On her effigy, the prayer towards her says : "Blessed Weaver, lady of grace, you who see our sin, our frail shells, our voices weak, and still offer your protection."
Thing is, the pilgrimage towards the citadel has been compared many, many times to a kind of culling to kill off any bug that may be too weak to become slaves to the citadel. So if Camora was part of the weavers who had that goal, why would she specifically be protecting people who are weak and cannot sing ? (That ability being essential for the chorals)
And while thinking about that, something hit me.
They didn't just spawn out of nowhere. That's a very well crafted public transport service, one that must've been built by one or more weavers. Why am I so confident about that ? Because there's a bellway entrance INSIDE the citadel. If it was a random common bug project, the weavers would've obviously exterminated the ones who wished to add this system.
To counter this, I believe the weavers who saw other as tools must've gotten rid of Keelal, closed all of the bellways and added the rule Sherma mentions about pilgrims not being allowed to use methods of transportation like the bellways.
Next, we have Camora, the "weaver of healing"
Her prayer mentions specifically healing bugs of other species that are attempting the pilgrimage. Thing is, once again this seems to be going against the idea of the rulers of the citadel. It is repeated several times that infirmity, sickness and old age are all massive sins in this religion. So if being injured is a sin, why would there be a weaver happily calling herself the goddess of healing ?
But there's no place of healing in the citadel ... Or is there ?
Now don't get me wrong. This place is absolutely terrifying and it apparently was built to experiment with silk, and the results we see are gruesome. But do we know for sure that they were always that violent ? Because we have proof that silk can be used to heal bug's wounds peacefully. And that seems to be a technique used by quite a few weavers. Binding.
I believe Camora was too nice and focused on healing people who were already fragile and weak, perhaps even creating the binding technique herself. Other weavers saw it as a waste of time and instead began to shift whiteward's use into more and more violent use of silk to see how far they could go out of morbid curiosity.
And finally, we have Atla, the "weaver of time"
I'm going to do a stretch here and go with a popular theory from the fandom : Atla and first sinner seem to be the same person. I won't develop it too much here, I'd say there's a good amount of theories explaining it out there.
According to her prayer, Atla is an historian. She keeps track of the events of this kingdom to make sure it's remembered. If she is the first sinner and she realized that she's been lied to all her life and gaslit to believe she's a goddess as someone who's supposed to make sure history is kept written down without any lies ... Yeah I bet she'd be PISSED.
Once again, I'd say Atla most definitely had influence in the citadel, and who better than an historian to build the memorium ?
There's no real reason for weavers to have built such place if they didn't care about it in some way. It could be just propaganda for the pilgrims who reached the citadel but y'know ... If you already dedicated your life to reach that place, I doubt you'd need to convince them any more about its good faith.
And what seemed to happen was pretty obvious. The slab seemingly was created specifically to punish and silence Atla for trying to bring up the truth. And once sealed, the remaining weavers did everything they wanted in the memorium, pretending that it would be here to preserve the memory of everything in this kingdom ... While also forever hiding the Verdania part of it.
With all of this, we would finally have an answer as to why Sherma seems to have faith based around trusting the weavers and why Shakra seems to despise them. Neither of them are wrong. Simply, one happened after the other, after the downfall of the people who tried to treat the weak with kindness