Topic's come up again, so thought I'd share an idea I've been noodling around with.
My thought is Ten Commandments. The paladin/anti-paladin codes the Gods supplements gave me the idea. First simply law/chaos/good/evil/neutral into a one line statement each. Create a 10 commandments for each Golarion god. The first is the statement of the God's law/chaos axis. The second is the statement of the God's good/evil axis. The rest are a list of how the god expects you to go about doing 1 and 2.
By doing it this way, you don't have to have just one universal interpretation of the alignments for any given action (which leads to no end of arguments), since some gods might go about it one way, some another, but you still have the one big theme to be able to tell one alignment from another, and since each god has a creed of dos and don'ts, players and GMs can get on the same page on what their character would or wouldn't do.
Trying to distill down the alignments to a core of what they're all about, here's what I came up with:
Law/Chaos:
Law: Follow this creed and make others to do likewise.
Neutral: Follow this creed.
Chaos: If you follow this creed, don't let others make you do otherwise.
Good/Evil:
Good: It's the duty of the strong few to protect the weak many.
Neutral: It's one's duty to protect one's own.
Evil: It's the duty of the weak many to serve the strong few.
So for example the ten commandments of a LG god would be:
1) Follow this creed and make others to do likewise.
2) It's the duty of the strong few to protect the weak many.
Then 3-10 Would be a list of dos and don't that explain how to do 1 & 2, and could be things like not harboring criminals, what's the difference between accepting a reward for completing a quest and extorting protection, etc.
Different lawful good gods would all have the same commandments 1&2, but different 3-10, showing their different priorities in how they expect people to do #1&2. For example, Erastil could have a line about not abandoning your village to fight someone else's battle, while Iomedae might have a line that it's a duty to go on pilgrimage to fight evil wherever it may be. Those both are ways the strong can protect the weak, but different ways of going about it.
This way common problems like what to do with prisoners can be given a clear answer, but the answer could be different between gods of a given alignment, letting the player pick exactly which creed they prefer, while also giving clear guidance on if they're following it or not.
I plan on cribbing commandments from the Gods supplements, especially from the Paladin/anti-paladin creeds of the various gods.
I agree with some of what Keshori said about law, as part of law that means following law that your character (or you) dont agree with. Especially if you are in a foreign land. (though Lawful Evil might go on a Crusade and try to turn everyone to his law)
I think that instead of having these commandments 'set in stone' (LOL) per-say. I would have the Characters who actually worship these deities. The Paladin/Anti-Paladins, Clerics, etc. Make their own interpretation of their Deity's Creed and have that be their guide for decision for the rest of the campaign. This will give even followers of one deity separation of interpretation of their gods wills.
This can be via regional practices of a particular deities teachings, or almost anything, but if you're putting this much weight on particular decision of a character and whether this is okay by their deity, then I would suggest having them make this Creed and agree that his character follows it (and that it fits with his deity)
Pathfinder has supplements like faiths of purity that offer paladin/anti paladin codes for almost all of the deities...Might give you a good starting place.
Edit: more careful reading of your post shows you already saw this