What does it mean to be devout if you suspect your god might be, uh, misusing you? Beyond memorizing scripture, anyone can do that.

What is the relationship of a worshipper to a god if the worshipper isn't sure (or isn't obliged to have faith in) the god being good, and knowing better than you do, and so on? Why even do it? Why not worship some other god, one that is actually Good and that doesn't have whatever qualities made Iomedae suspicious of Aroden? Is the answer simply that it was Aroden who happened to empower her?

This is Iomedae's holy book, not Aroden's, but she seems to have been brought up Arodenite, and to be really bought in to the project of civilization and Law and the improvement of things over time and the construction of structures that will support that, and those seem to be, at the time she was not yet herself a god, his deal. He picked a lot of paladins, apparently, her uncle was one too, and he seldom tolerated an Evil cleric who continued that way for very long, and it's not obvious why he'd be LN if he was so bought in on Good (from the Acts alone) but Iomedae is ultimately sold; she gets a legit vision that he does promise that she will not be turned against her purposes. There's some poetic language repeated more than once about how in Iomedae's opinion Law and Good are not the main thing she (or Aroden) are after but they are both in search of the secret third thing* which marries the two. She doesn't seem to have any specific reason to be suspicious of Aroden besides that any paladin order she joins will require some pretty heavy oaths and breaking them would be unthinkable.

*it doesn't literally say "secret third thing"

Is that 'civilization' as in 'the subjugation, enslavement, et cetera of all non-human species' or are there any other qualities mentioned?

When it comes up she seems to be against slavery, if in limited terms that might be intended to preserve her audience's attention! She is pretty up on humans, admittedly, and mostly does not mention folks like elves and dwarves at this juncture in the book.

...Tanya is curious how paladins work, socially speaking. In this story, a (presumably not-very-ordinary) teenage girl is suddenly given magic and a seal of approval by her god, and as a result she sets out to learn about him and what she's meant to (or wants to) do with her newfound power. Wouldn't it make more sense to do it the other way around? Have people apply to seminary, or whatever they have, receive some education and maybe training, and then have the god choose between them? Why does the god need to suddenly upend someone's life and obviate all their previous plans? That's probably not important to the story, though, and it likely works differently today anyway.

She's not sure what she's supposed to be learning from this. She doesn't expect to understand religious scripture without a lot of context and explaining, at least not the way it's meant to be understood, but Select Oliva knew that and still recommended that she read it.

A religious story about a single hero's life would normally be pointing out things she did (or thought, believed, etc.) that most people in her situation wouldn't. So far the only thing that seems to pattern-match that is Iomedae doubting whether her god was acting in her best interests, while believing that he was acting in the best interests of the project of 'civilization'. That makes sense; most people need to be reminded not to trust gods blindly (or at all). Well, and there's the fact that Aroden noticed and chose her in the first place, but that without any details about who Iomedae was as a person before that it's hard to make any use of that fact. Beyond that, Tanya doesn't feel like her understanding of the relationship between individual and greater Good is improved by considering Iomedae's example, but she might well be missing the right exegesis.

She reads on. Maybe Iomedae will get around to explicitly preaching or something.

If you read between the lines he might have chosen her remarkably young and with remarkably little provocation to avoid her having a marriage arranged or anything already at the time; she was of a social class that might have done that sort of thing with its teenage girls.

Iomedae does give some sermons that are rendered in the text! They are of course Arodenite sermons, but the ones selected for inclusion in the Acts are more about Law and Good and how people shouldn't let the undead take over the world. It is remarked that she was very splendid and persuasive and inspired a lot of people to changes of heart that could get them cleric'd or paladin'd on the spot, and many more to enlist in the Taldane army that was meant to resist Tar-Baphon the Lich King, who had various scary unusual properties as undead go such as an unlimited number of undead it was possible for him to control and allies/minions in the form of assorted other unique and intelligent undead. The book is careful to remark that a preacher's splendor is not a great way to choose a career and Iomedae learned to be more careful with how intently she impressed upon people the importance of the Crusade; no Crusade does without farmers and who should be a farmer and who should be a soldier ought to be governed a great deal by what is good for each individual man deciding either way and she had to learn to see into people's hearts if they were right for the Crusade and the Crusade right for them even considering its overwhelming import.

...that is excellent advice. Not a viewpoint the government would normally promote, but a church of course has different considerations. 

Convincing people to volunteer for a truly necessary war is extremely impressive if you can do it by reasoned argument, and not at all impressive if you do it by having literally god-given charisma. That's barely any better than enchanting them. It's good that Iomedae regretted it, and it's very good that she (and her church) admit to it and point it out in their holy book. Most holy books don't catalog the early mistakes of their gods, and this makes (is probably calculated to make) a very good impression.

Also: if the war was so important, why was she recruiting volunteers and not conscripting them? Well, the government would be conscripting them and not the church, with its own idea towards who ought to stay a farmer, but still! Did they not use conscription to stop the army of undead that seriously threatened to conquer the entire world?

Something is definitely missing from this picture. It may or may not be of religious or moral significance.

What can Tanya personally learn from this?

She wasn't teaching people to be more Good. She almost certainly couldn't if she tried, but more importantly the idea would never have occurred to her. She didn't try to do things outside her duties unless they would benefit her. Making her men more altruistic by preaching at them would have struck her as a complete non sequitur. Isn't that the army chaplains' job? Specialization and division of labour are the bedrock of society, and that goes double in wartime.

...that's not the point. It's not as if she checked if the chaplains were doing their job with her men, she only cared that they didn't interfere with hers. Well, it's rather doubtful whether army chaplains actually help people be Good (as opposed to merely loyal and brave), since their job is to explain to soldiers that they're fighting in a righteous God-blessed cause absolutely regardless of any facts on the ground, and also regardless of which religion they happen to be a priest of. But Tanya didn't consider counteracting their influence, either. (It would not have been good for her career!) 

She did absolutely everything she could to protect her soldiers on the battlefield, but only in order to make them better soldiers. She prayed to Being X in front of them and hated herself for it and eventually stopped, but the reason she stopped wasn't that she was setting a bad example or teaching the wrong lesson. (And she's really lucky none of them ever emulated her in that particular perversion, at least not out loud where she could hear them!)

She wasn't doing recruiting for the army, either. ...no, that's not actually true. She personally interviewed, picked, trained and picked again (and mostly discarded) the forty-eight mages who would become her 203rd battalion. The candidates were already military mages, of course, but they volunteered for her interview and for the transfer and she wrote the text that convinced them to do so. (She was trying to produce text that would convince them not to do so, which probably says something about Tanya's charisma, but she really couldn't say what.) She decided, in large measure, who would join a new experimental elite unit. And her track record leading them isn't spotless, she lost nearly a whole company of men on that disastrous mission attacking the Queen of Anjou, but that's still a better track record than the army-wide average. And her men (those who survived) are elite, decorated veterans with a distinguished record. Tanya thinks she did well by them. But - she wasn't trying to.

Isn't it ridiculous, to try to do well by your men? Once you (and they) have committed to fighting in war, and accepted the mission objectives, isn't it your supreme duty to fulfill those objectives? And if you're trying to be Good, isn't it crazy to be worried about not doing well by your men, whom you reared and led and protected, rather than the enemy your job was to kill or the unfortunate civilians who got caught in between?

...

What happens next in the book?

Iomedae has to found her own order of paladins because the ones that exist do not suit her - they are all doing good work but they're pretty locked in to what work was good when they were founded, and the selection of them that'll take women is pretty dismal. She gathers up the first batch of the Knights of Ozem and there's space dedicated to the code of conduct and whatnot. Also, she gets herself more and more firmly attached to the Shining Cruasade, which (obviously) she was not yet commanding while still a teenager. The Crusade is direly in need but is being made, by enemy action, to seem less so, and by failure of the flow of information within the Taldan Empire to appear even less so than that to the people who make important decisions, and there's slightly oblique content about heresy laws (against, obliquely) and there's battles to break it up a bit and then there's a lot of stuff about intervention budget - a concept that Iomedae may not have literally quite personally invented whole cloth but definitely made some major innovations in. She does (commissions) (through her superior officer Arnisant) a souped-up fancy Commune to find out what Aroden wants them to do and gets the go-ahead to Call his herald Arazni, a neutral good demigoddess who in life was an archmage specialized in arcane botany to get through the Age of Darkness, this part would make for a nice little solo aria for whoever you cast as Arazni if you were performing it.

At this juncture the library is closing.

Tanya has to organize her own battalion of mages because the ones that exist do not suit her that is not a useful analogy.

The Germanian army certainly had its issues with prejudice against women when it first began recruiting mages. However, the brass would never tolerate a unit that refused to accept half the mages in the recruitment pool. Iomedae was operating in a less centralized world, where private military 'orders' were legal and could decide whether and on what conditions to fight in the war. Perhaps Taldor was incapable of conscripting its mages because of political dysfunction and infighting, or perhaps the central government simply could not enforce its power over the border provinces even in an emergency, Iomedae was from - somewhere Tanya can't place on a map but she doesn't want to bother the Nethysians for a political map seven centuries out of date.

Tanya is used to holding militaries to a high standard, but nations can behave idiotically no less than individuals. Just look at the Entente's internal politics which started this whole mess. (Tanya's mess, not Iomedae's.) A government that doesn't know or refuses to acknowledge that the war it is already fighting is an existential one that it is badly losing is - painful. Iomedae (more relevantly, her superior officer Arnisant, though he might not have been sufficiently high-ranked) did not resort to drastic measures and attempt to replace the incompetent government. But that is because she had a higher authority to call on; the god they all (nominally?) obeyed. Tanya... doesn't know how to apply that to her own situation. She could read it as an endorsement of them trying to do something anyway, but perhaps she shouldn't be reading the Acts as an endorsement of anything she ever did.

Intervention budget treaties constraining the gods are clearly a very important fact. It explains some things, and implies a lot of other things which Tanya hasn't thought through yet, and also raises a host of additional questions. To begin with, wouldn't the very first communication to your mortal followers explain divine budgets and how to use them efficiently? However much that communication costs, surely it will pay for itself by its very nature? And if you want to send a powerful agent to fight in a war - a big intervention! - surely communicating that you want to do that and that they should call her is a tiny one in comparison? How can you get anything done by relying on one of your mortal followers to happen to ask you whether you want to do the thing you were planning to do all along?

In fact, if she's such a powerful archmage, why can't she come over herself? If the mortals call her first, does that mean she can do anything she likes and it doesn't come out of her budget? But then, why didn't Taldor regularly call every Heavenly ally they have in case they wanted to come help until one of them accepted the call? Arazni was in a unique position as Aroden's herald, which made her an obvious target... maybe the calling spell is extremely expensive, and so is the Commune, but why can't you do a regular Sending to check if they want to be called? Tanya is lacking too many facts to make any sense of the story being told here. (Or perhaps divine budgets are extremely complicated, the book doesn't explain them well enough for Tanya to reason about them, and only a unique genius like Iomedae could have figured it out.)

She's not here to read a military history of the Shining Crusade, though, and the book clearly isn't one. What are the philosophical or moral points being made by the story?

Iomedae doesn't automatically trust her fellow mortals, any more than she does her god. She has exacting standards and she is unafraid to challenge existing institutions and if they don't suit her to found her own. When she (correctly) thinks the higher-ups are failing at their jobs, she bypasses half an army's worth of a chain of command to appeal directly to the supreme commander (and is proven right, otherwise you wouldn't be reading her story). 

Not only is she almost always right, she is always - taking initiative. Her accomplishments so far aren't as a great soldier or mage or tactician, someone who achieves unprecedented success in carrying out the plans of others in a machine that relies on everyone doing their job. Not even as a great reformer; maybe that will come later once she commands the entire Shining Crusade, but she ended up with her own country instead of taking over Taldor and Tanya can begin to see why. She comes across as - an outsider. Sharing the organization's ultimate goal (victory over Tar-Baphon) as a personal one, joining the army only inasfar it serves that goal, and being unafraid to criticise it both implicitly and explicitly.

If that's the model the Iomedaeans strive to emulate, it's no wonder they wouldn't appreciate Tanya. And if that's what's needed to be Good...

She walks home with Belmarniss lost in thought.

Belmarniss has wheedled from the library an overnight borrowing of Archmages Through History; she doesn't read it while she walks but she obviously kind of wishes it were smart for her to do that.

Tanya is very familiar with that attitude! It's always so tempting to work while you walk, if you can't fly. But you shouldn't risk getting so engrossed that you'll walk in front of a horse.

Or that you'll forget to cast Root.

Anyway she's back to it as soon as they get to their inn for the night.

That's fine, Tanya isn't especially looking for a conversation right now. She doesn't even want to keep reading the Acts. A lot of things have happened and she hasn't processed them properly yet. She feels she had an insight, realized she had been wrong, and still isn't sure what would be right instead.

With long practice, she folds her military jacket on the bedside table and then... just sits and stares at it, for a while.

These are her everyday working clothes. Not at all like her dress uniform. A ribbon bar, a modest black cross. She should have shot that one too. The distinguished record of a excellent field officer with five years' service in wartime, compressed to a few centimeters of cloth.

Some of those colors stand for a pair of silver wings, not that anyone could possibly tell out in the field. She hasn't needed to wear the real article to assert her standing in... what feels like a very long time. It made waves and did wonders for her career at the time, but these days her name and mana signature precede her. But it was her first big accomplishment, a recognition of the great value she'd delivered to the organization... or so she thought, anyway.

The Silver Wings Assault Medal is awarded to soldiers who, by gravely risking their lives, rescue an entire other unit. That unit's commander must nominate them for the award, not their own commanding officer. The silver wings are said to symbolize these heroes' status as the guardian angels of the battlefield. An apt name, because they are rarely awarded to a living recipient. The regulations even have a unique dispensation for it to be presented to the recipient’s hat and rifle.

What was she even thinking at the time?

Ahh, war is glorious. The Entente Alliance has attacked us without even properly mobilizing and now the Empire's well-honed war machine is rolling right over it. By participating in a series of winning battles, I can earn a quick promotion right out of college. I am literally giddy with anticipation!

A company of enemy mages headed my way. Reinforcements? Ten minutes out. Six. I'm ordered to delay them for six minutes. Alone and without even a rifle! But if I retreat they'll get their shot at the artillery blasting the Entente's retreat. Permission to withdraw!! Denied. A single mage is worth much less than an artillery battalion. If I can delay them, that is.

Alone against a company of enemy elites? That's just ordering me to die. But retreating without permission is also death. If I have to die, I'm taking some of these bastards with me. Without a future to worry about, I can inject all the stimulants at once!

Kill or be killed. That makes this my personal war. Aaah, the rush! I'm giddy with excitement! What an honour, what a wonderful moment! This is so much fun, I can barely contain myself! Good, CP heard me on the open mike. They can testify how eager I was to fight. If I can withdraw later, I'm sure to get accolades. I'm the star of the battlefield, getting to take on a whole army by myself! It really is a good day to die! How can I please my superior officers with my performance? If I put up a fight I'll be allowed to withdraw, but the enemy must not win!

I've killed three of them already. Is that impressive enough? This way I can say I did everything I could. Ah, but they're upset and they're trying to rush me. That just makes it easier to blow them up, even if I'm too close -

...

She wants to buy civilian dress.

Clothes are expensive here, though. It would probably feed an orphan for a month, or something. And it's not her money.

It can wait.

Belmarniss finishes the chapter on Baba Yaga and closes the book for the night.

Tanya hates the idea of declaring everything she did for the past five years a mistake.

This is entirely unsurprising. That's what humans are like, even those who call themselves rational. They build up a self-image, attachments, a sense of their own value, a way to feel validated. Obviously it feels terrible to throw all that away. That doesn't mean she shouldn't do it, if it's the right thing to do and/or gets her out of Hell.

Was it really all for nothing? All that pain and desperate struggle. Should she have told her men to sit down and passively await the end?

Is the world any better for what they did? Are they any better?

Isn't it terribly presumptuous, to try to answer such a question?

...

She's a soldier. She can go to sleep.

In the morning the inn has pastries with cheese in them!

They are appreciated!

Tanya is going to return the spare books that the library also has to the Iomedaean church. And if Select Oliva is there, she'd like to ask him what exactly she should be looking for in the Acts.

It's clearly not meant to be a military history, that's just Tanya's instincts misfiring. She expects the reader would normally learn by noticing the ways Iomedae is unusual, the things she did that someone else in her place wouldn't have. The problem Tanya is having is that she's not sure what others in her place would have done, because she's lacking so much context. And she's afraid she's missing a lot of important cues because of that.

If she will wait for services and a few post-services questions from parishoners to be over, she can talk to Oliva! His office is in the same place as last time.

How long is that? She can come back later instead... she should really figure out when they hold services, if she's going to be visiting them a lot.