In this chapter, a nameless prophet proclaims disaster against Jeroboam, and then meets his own misfortune.
I find this chapter both fascinating and more than a little confusing. I'll try to explain it the best that I can.
First of all, the clear purpose of this chapter is to rebuke Jeroboam. As the author made clear in the previous chapter, Jeroboam was sinning in a variety of ways by constructing his own religion, and here we see Jeroboam offering incense to the idol that he had made, and a prophet comes from the LORD to rebuke him for it and promise destruction for the altar and priesthood that he made. Furthermore, the prophet is declaring that it would be a descendant of David, Jeroboam's rival, that would destroy this altar. Keep in mind, Jeroboam built it to secure his kingdom against the threat of Rehoboam, David's descendant.
Some notes from Rashi. Rashi points out that the LORD punished Jeroboam by shriveling his hand when he stretched it out against the prophet, but did not shrivel his hand when Jeroboam stretched it out to offer a sacrifice to an idol. By this, he avenged the honor of a righteous man more than his own honor. It's interesting, but I think that feels consistent with what I've seen of the LORD, because I think the LORD is more concerned about protecting and honoring his children than himself. This is part of his humility. Rashi also points out that in verse 6, the king says "the LORD your God", so even in the midst of his rebuke, he does not consider the LORD to be his own god. Jeroboam is not going to repent.
This first part of the story is straightforward. The prophet came, delivered his message, and was protected from harm by the LORD. The prophet rebuked Jeroboam with his words, and when Jeroboam attempted to punish him (probably by death), the LORD rebuked Jeroboam by shriveling his hand. At the end, the prophet is on his way out of the country, with mission accomplished. The second part of the story is a bit stranger, as the prophet's life comes to an unexpected and unfortunate end.
We learn about a second, old prophet who lived in Bethel. The first thing we should realize is that this prophet is living in the same town as the false idol, which casts aspersions over his moral character and loyalty to the LORD. I think the descriptions of the old prophet in this chapter are ambiguous; it doesn't say that the prophet is a false prophet or that he worshiped other gods. What it says is that he lied. However, after the true prophet dies, the old prophet mourns over him, which implies godly character.
So, I have a hard time analyzing the character of the old prophet. In general, I do not think the old prophet is a particularly godly man. I think he mourns over the death of the young prophet because of remorse. He knows that his actions caused the young prophet to die, and he's sorry for it. But he is not acting like a godly man. He is living in the midst of idolatry and doesn't challenge it. In fact, we could imagine if the old prophet were still following the LORD, he would have been the one to bring a message of rebuke to Jeroboam. Secondly, the old prophet lies to the young prophet and tricks him into breaking the command of the LORD to not eat anything in that country.
And that's another point. The young prophet was commanded to not eat anything in that country because it was a country in rebellion against the LORD, and in a metaphorical sense he was supposed to treat it as unclean. The young prophet was supposed to go in and do his job and leave, not to dwell in that place and implicitly legitimize their behavior by fellowshipping with any of the people of that country. If that is how the young prophet is supposed to behave, then how is it okay that the old prophet would live in Bethel, one of the two centers of idolatry in the northern kingdom? It is not.
All of these factors indicate that the old prophet is to some extent backslidden. However, in verse 20 it says the word of the LORD came to the old prophet. How can a backslidden, lying and possibly idolatrous prophet also prophesy the word of God? The answer is exactly what it looks like: God is willing to speak through even sinful prophets. I should remind my readers of Balaam, from Numbers 22-24, who prophesied on behalf of the LORD multiple times and in Num 24:2 even has the "spirit of God come upon him". This, in spite of the fact that Balaam did not worship the LORD and was almost certainly an idolater. In general, I believe the LORD is willing to work through people who do not follow him fully or perhaps do not even follow him at all.
There are actually a lot of stories about this sort of thing, and Balaam and the old prophet are just two of them. The general principle is this: God is willing to work through people with giftings that exceed their character. There are prophets in the world who can do profound things and even perform miracles, yet have deeply compromised personal character or devotion to the LORD. This is undoubtedly one of those cases. Now, one might ask why does God work through sinful people, especially a person like Balaam who was not a follower of the LORD? I discussed this topic to some extent in 1 Samuel 6 which also contains pagan prophets/diviners somehow discerning the LORD's will. I won't go into this subject in a whole lot of depth here, but the bible is clear that God can and does speak to non-believers, and furthermore, the LORD uses non-believers to accomplish his purposes in the earth. While I do believe the old prophet is a follower of the LORD to some extent, simply having the word of the LORD come to him does not validate his lifestyle, personal character or other decisions in this chapter.
In the end, the old prophet mourns over the death of the young prophet and identifies himself with the young prophet by asking that their bones be buried together. He knows the truth of the young prophet's words, and that his actions resulted in the young prophet dying. And, I'm not sure what else there is to say about this. He sinned, he knows it, and it's not clear if he ever left the northern kingdom or did anything to serve the LORD again. The text does not inform us what happens to the old prophet.
One last minor note is that this chapter contains the first reference to "Samaria". This is an alternate name for the northern kingdom (which is sometimes called Israel). It is called Samaria after the capital city of the north, Samaria. The name of the capital city and the name of the kingdom are sometimes used interchangeably. So, in case things are not confusing enough, there is another proper name that is going to be thrown around without explanation. Yay!