The last book of the Old Testament is that of the prophet Malachi, who was a contemporary (or nearly so) of Nehemiah.  He lived almost a century after the other post-Exile prophets Haggai and Zechariah.  Those men had assisted Zerubbabel the governor and Joshua the priest at the time the Temple was rebuilt.  Similarly, Malachi supported the reforms of Nehemiah.  He brought the "word of the Lord" against the same evils (idolatry, laxity, intermarriage) that Nehemiah opposed.

          

We know nothing about Malachi.  Since his name means "My Messenger," and this term occurs in the book (Mal 2:7, Mal 3:1), it is even possible that "Malachi" is a title rather than a proper name.

         

In Judah at this time, the Jews still faced occasional opposition from neighbors.   But the biggest problems were internal.  The energies of renewal, rebuilding, and reform fanned by Zerubbabel, Haggai, and Zechariah, and later by Ezra and Nehemiah, had fizzled out.  The glories and prosperity announced by generations of prophets hadn’t materialized, and the people were disheartened.  The spiritual abuses described by Malachi were similar to those addressed in Nehemiah’s final reforms (Neh 13) — halfhearted religious observances and intermarriage with Gentile idolaters. 

         

Malachi frequently presents a dialogue between the Lord and Israel.  The human responses are introduced with the words, "But you ask."  This device highlights Israel’s state of mind, a complex blend of rebellion and unbelief, anger and doubt.  Israel has turned aside from the Lord (Mal 2:8, Mal 3:7), but if she returns to Him He will return to her.  The Lord’s messengers are those who turn others from sin to righteousness, both now and at the end of time (Mal 2:6, Mal 4:6).  "Turning" may almost be said to structure the book, as the first two chapters describe Israel’s turning away and the last two announce the Lord’s return.