"A Plan of Thine Adversary" (Alma 12:5)
In Alma 11, Zeezrom (a lawyer) tried to get Amulek (a missionary) to deny his testimony of Christ by offering him a ridiculous amount of money (a judge in those days made a senum a day (11:3), and Zeezrom offered Amulek six ontis (11:22), which is equal to 42 senums (11:11-13), so Zeezrom offered Amulek 42 times whatever a judge's daily wage was). In response to this bribery, Amulek totally confounded Zeezrom by teaching pure doctrine. Now that we're in chapter 12, Zeezrom is asking honest questions and Alma is teaching him beautiful truths.
In verse 5, Alma says to Zeezrom, "Now this [the bribery attempt] was a plan of thine adversary, and he hath exercised his power in thee." This is, to me, a fascinating statement. I have often heard the devil referred to as the adversary, but here Alma calls him Zeezrom's adversary. There's a great truth here: the devil is never your friend. No matter what you do to serve the guy, he's never going to support you. (We see this a few chapters later when Korihor (and anti-Christ) is killed by some Zoramites (who were also opposed to Christianity).)
"What Is Meant by the Chains of Hell" (Alma 12:9-11)
In v9-11, Alma teaches Zeezrom that, if a man is willing to obey God and receive His word, he will eventually come to know the mysteries of God "in full." BUT, for those who harden their hearts, "to them is given the lesser portion of the word until they know nothing concerning his mysteries; and then they are taken captive by the devil, and led by his will down to destruction. Now this is what is meant by the chains of hell." Might we postulate, then, that
ignorance = chains of hell
I'm not entirely convinced that ignorance is the best word (though it might be made more accurate with a descriptor like "willful"), but I think that the above statement approaches truth (perhaps asymptotically, I don't know). Either way, I think it's safe to say that we should ever seek to be learning, and, if one day we find ourselves no longer learning, then we probably need to repent and change lest we be "taken captive by the devil."
"After Having Made Known unto Them the Plan of Redemption" (Alma 12:32)
Just kind of in passing, Alma says (speaking of Adam and Eve) that "God gave them commandments, after having made known unto them the plan of redemption" (12:32). The plan of salvation (or redemption or happiness or--lots of other things) gives context to the commandments. It's hard for someone to understand the purpose of commandments if they don't have some understanding of the overarching reason for life and existence in general. The plan of salvation is about as fundamental as doctrine gets. I propose that the plan of salvation is the restored gospel of Jesus Christ; if you can think of a "doctrine" that is not some how included in the plan of salvation, then it probably isn't terribly pertinent to salvation (or, worse yet, it may simply not be true).
We, Us, Our (Alma 12:37)
I really appreciate that, in the closing verse of this sermon, when Alma encourages everyone to repent, he doesn't exclude himself from the admonition:
And now, my brethren, seeing we know these things, and they are true, let us repent, and harden not our hearts, that we provoke not the Lord our God to pull down his wrath upon us [...] but lest us ender into the rest of God, which is prepared according to his word.
I really like this about the righteous leaders (both political and spiritual) in the Book of Mormon. King Benjamin labored for his own support (Mosiah 2:12, 24), and Alma, as chief judge, fought on the front lines against the Amlicites and the Lamanites (Alma 2:29-34). This was the typical state of affairs among the Nephites when they were righteous. In Alma 1:26, we learn that
And when the priests left their labor to impart the word of God unto the people, the people also left their labors to hear the word of God. And when the priest had imparted unto them the word of God they all returned again diligently unto their labors; and the priest, not esteeming himself above his hearers, for the preacher was no better than the hearer, neither was the teacher any better than the learner; and thus they were all equal, and they did all labor, every man according to his strength.
And... uh.... Yeah. That's all. Sooooooooooo--[FULL STOP]