v. 7 This is what he showed me: the Lord was standing beside a wall built with a plumb line, with a plumb line in his hand.
There is not much good news in this passage. The verdict is that Israel (also called Jacob and Isaac in the passage) will be destroyed. Their crimes against justice have simply been too much, are too systemic. That is what the plumb line is about. The plumb line was used to ascertain true vertical for a structure. Israel's was so far out of true that it could not be recovered from. There is deep sadness in the text, especially for anyone who reads and knows what is to come. Israel will indeed be destroyed by the Assyrians and, unlike the exile in Babylon of the southern kingdom sometime in the years ahead, they will never be heard from again. They will for ever become "the lost tribes of Israel."
In the passage Amos has three visions. After the first two he pleads with God to relent and God says, "It shall not be." But after the third he doesn't even try to plead. He seems to know it would be useless.
The good news for us is that we have one who pleads for us, Jesus, and he will always be heard. And he constantly is our plumb line, the standard by which we measure what is true and, in fact, the way in which true is made right again.