The main concern for any writer is to pass along information in the best way they can. If they're writing nonfiction, that's going to be in an understandable manner. If they're writing fiction, they will want to use an entertaining manner.
What was the Monsieur’s main concern
his main concern is about his reputation....
Haimon's main concern is that he be with antigone and that his father would let them be. Creon main concern is that haimon and antigone does not get married.
The afterlife was a main concern of the Egyptian civilization.
my concern is (What is causing the Headache)
Paul was the main writer of letters (epistles) in the New Testament.
In a nonfiction work, a writer's main idea is his or her purpose for writing.
Luke because he was a gentile himslef
In conjunction with the FOMC and the twelve Reserve Banks, the Board of Governors' main concern is the development of monetary policy.
A History writer
The afterlife
the human figure