Malachi, the final book of the Old Testament in the Christian canon, is among the shortest books of the Minor Prophets and among the last to have been written. The name “Malachi” is likely the prophet’s name, though some think it is a title “my messenger,” which is its literal meaning in Hebrew.
The book does not give any clear indication as to when Malachi carried out his prophetic ministry. Since Malachi shares some themes with Nehemiah, namely denouncing unfaithfulness to the law, it is likely that Malachi was a contemporary of Nehemiah. In particular, Malachi may have been around during the latter part of Nehemiah’s efforts to establish covenant faithfulness among the returned population from Babylon around 433 BC.
During this time, the people had been back in the homeland for over 100 years. After all this time, the glory years predicted by earlier prophets like Haggai had not come about. It seemed like God was not really in the land, dwelling in the temple, and poised to return to Judah.
According to Malachi, the reason for this delay is the priests’ unfaithfulness to the law, namely, for offering blemished sacrifices and for failing to uphold justice. Judah as a whole has fallen into idolatry, which is described as adultery. To correct the situation, God will send Malachi (or “my messenger”) to prepare the way of the Lord. God will return to the temple—not in splendor and glory as in the days of Solomon—but as a refiner’s fire, purifying the people and setting things right. The Gospels apply this to the ministry of John the Baptist, whose message of repentance prepared the way for Jesus’ ministry.
For Malachi, God’s return to the temple (i.e., the “Day of the Lord,”) would expose the distinction between the righteous and the wicked. That judgment would be like a raging furnace. The disobedient will be burned but the righteous will be healed. Until that time, the people are admonished to adhere to the Law of Moses and wait for “Elijah” to come and preach repentance. The prophet Elijah (2 Kings 2) did not die but was taken up to heaven in a chariot. This gave rise to expectations that Elijah would one day return. It is for this reason that it was this image in particular that was also applied by the Gospel writers to John the Baptist.