The original target audience
While plenty has been written about authors and dates in this study, the third part of determining the original message also depends on the original target audience. A lot of this also depends on the date of the book as cultures change over time as well as people's thinking.
Imagine if Hosea had been written to the church in Jerusalem in 60 AD. We would conclude that that church had some serious issues with idolatry and spiritual adultery! But of course, Hosea was written to the northern kingdom of Israel, which had a sordid history of apostasy and Baal worship.
Sometimes, the book itself will be addressed to a certain person, church, group, or nation. We can be very sure of the original target audience in this case. 1 and 2 Timothy were addressed to ...Timothy. Titus to Titus. Romans to the church in Rome. You get the idea.
So, questions to ask about the original target audience:
1. Are they Old Testament people or New Testament people?
2. Are they Jewish, Gentile, or The Church (mix of both)?
3. If Jewish (Old Testament), are they in the divided kingdom and if so, which one?
4. Also if Jewish, are they pre or post exile to Assyria/Babylon? Or are they in exile at the date of the book?
5. Do they live in relative peace or persecution?
6. If Jewish (Old Testament) do they have a good king or a bad king leading the nation?
7. What was the attitude of the audience to the message? Hostile? Repentant? Accepting?
8. What other prophets may have been preaching at the same time in the same area or in the other kingdom, if divided?
9. What is the spiritual condition of the church, individual, or group that the book is addressed to? Faithful? Wavering? Out of control?
In 1 Corinthians, Paul uses the phrase "now concerning" 5 times with the first occurrence in 7:1: Now concerning the things about which you wrote... Four more times in the remainder of the book, Paul addresses things that the Corinthian church wrote to him about. The contents of chapters 7-16 were teachings that the Corinthian church asked for clarification on. Chapters 1-6 were teachings that the Corinthians didn't necessarily want brought up...
Another passage that brings out the importance of the original target audience is the letters to the seven churches in Revelation. Christ did not address the loss of Smyrna's first love; no, Ephesus was guilty of that. Just as the Lord personalizes each of the seven letters, so He does with the rest of Scripture.