Isaiah 9:11 in the King James is- “Therefore the Lord shall set up the adversaries of Rezin against him and join his enemies together.” I guess the first thing to look at is, who is Rezin.
Rezin is the king of Aram and an ally of Pekah king of Israel (northern kingdom). Their stories are in 2 Kings 15 and 16, 2 Chronicles 28, and Isaiah 7 and 9. This is the time of Ahaz king of Judea (he did not do right in the eyes of the Lord) and the prophet Isaiah. As enemies go, he did not last long. Rezin and Pekah harassed Judah and caused a problem (2 Chronicles 28) but did not overpower Ahaz. The attack is recorded in Isaiah 7, which also contains the message about Immanuel. 7:8 has a most unusual time prediction of sixty-five years for Ephraim (Samaria) to be scattered and not be “a people”.
The second thing to look at is who his enemies were. Ahaz bribed the king of Assyria to attack Rezin (Damascus), he also marched on Samaria and deported the inhabitants of both countries to Assyria. Israel’s final deportation would come later-2 Kings 17.
Isaiah 9 also contains a messianic prophecy. The section of 9:8 to 10:4 is a message to Jacob (especially Ephraim and Samaria) about their pride and arrogance. It sounds like it could have come from Amos or Hosea. God did not forget Ephraim, but He did punish them. There are numerous words about God restoring Ephraim and Israel. To be fair Judah/Jerusalem was not acting right and under Ahaz, they really ignored God and the way of David.
My takeaway from the study of Isaiah 911 is
- God watches over His chosen people.
- The Father directs enemies to get His people’s attention when they will not listen to Him.
- God has good for His people when they return to the Father and rest in His righteousness and salvation.
Further Study-Find examples of God’s promise to restore Israel and Ephraim in Isaiah, Hosea, Amos, and Micah.
Mark's Bible Study 
Thank you, Mark! It is always good to be reminded that Isaiah (and all the biblical prophets) were deeply involved in the times of Israel recorded in Samuel-Nehemiah. This is becoming more important to me as I study the Word. And also important as we listen to the true prophets that God has raised up now with a strong message for what He is doing today.
You are welcome. I am trying to group the prophets to see similar messages. Setting the prophets with external enemies has also added to the learning curve.
Noted your references to Amos! I just started a Bible study by the same name with the ladies group at church. Your takeaways on this lesson run along a similar theme to what we are seeing through that study. My initial response to Amos was who on earth would want to study so much gloom and doom. But there is good stuff if you know how to look for it.😊
I think there is a pattern of “doom and gloom” offset by a word of hope and direction.
There is definitely that!
The author of our study, Jennifer Rothschild, has subtitled her book, “ The God Life is the Good Life”. In the first lesson, she points out how God judges Judah’s neighbors for their sins against his people and so we can live in the assurance of God’s care for us.