>If a priest were to sacrifice a person for the sun to rise the next day, and in reality the sacrifice bares no effect on the sun rising - then that would mean the priest's logic is flawed; it's not logical.
You need to keep in mind the distinction between Logic (rationality) and Experience (empiricism).
Something is only illogical if it's axioms (it's initial statements of truth) create contradictions. The Aztec Priest is acting under a system of logic. The only way you have to disprove him is to resort to empirical observation, You prevent him from sacrifice, show him the next morning that the sun still rises. To be clear though, you're aren't disproving his initial logical system, you're resorting to empirical observation (the opposite of rationality and logic).
>Do you agree that 'illogical' is the opposite of 'logical'?
No. The opposite of logic is empiricism. Illogic is something that occurs when a system of axioms create contradiction. You start with a set of assumptions, and if at the end you get a=not-a, then you have an illogical system.
>The one context immutable to your experience is your experience itself.
This is empiricism, not logic, and it has a whole host of critiques. Including the ability to misperceive through delusion, mistake, confusion, hallucination, brain injury, etc. Drop some acid. You'll learn just how mutable your personal expierence is. One time I forgot my name, identity, where I was, my friends names and I even forgot the fact I took acid.
>And, if there is no afterlife, nothing that happens when after I die inherently matters to my experience. Which is to say, it doesn't *logically* matter to me.
You should be able to see how these are subjective criteria. If you don't care about what happens after your expierence, that's on you. That's the axiom from which you draw logical conclusions. But no one else has to accept this axiom as a foundation form which to proceed to logical arguments. Anyone with religious notions of eternity (like the aztec priest), will not give a shit about their own personal experience. They start in a very different place (The Sun will not rise without blood) and proceed to logical conclusions (I must sacrifice humans on the pyramid).