The Biblical evidence is in the account of Malachi Chapter One itself, which identifies the author of the Book of Malachi as the Prophet Malachi. “The burden of the word of the Lord to Israel by Malachi.” Malachi 1:1
The Book was written between 440 and 400 B.C. The Book of Malachi is an oracle: its the word of the Lord to Israel through Malachi, this was God’s warning through to tell the people to turn back to God. As the final book of the Old Testament closes, the pronouncement of God’s justice and the promise of His restoration through the coming Messiah is ringing in the ears of the Israelites. Four hundred years of silence ensues, ending with a similar message from God’s next prophet, John the Baptist, proclaiming, “Repent, for the kingdom of heaven is near” (Matthew 3:2).
Malachi wrote the words of the Lord to God’s chosen people who had gone astray, especially the priests who had turned from the Lord. Priests were not treating the sacrifices they were to make to God seriously. Animals with blemishes were being sacrificed even though the law demanded animals without defect (Deuteronomy 15:21). The men of Judah were dealing with the wives of their youth treacherously and wondering why God would not accept their sacrifices. Also, people were not tithing as they should have been (Leviticus 27:30, 32). But in spite of the people’s sin and turning away from God, Malachi reiterates God’s love for His people (Malachi 1:1–5) and His promises of a coming Messiah (Malachi 2:17–3:5).
Malachi 3:1–6 is a prophecy concerning John the Baptist. He was the Messenger of the Lord sent to prepare the way (Matthew 11:10) for the Messiah, Jesus the Christ. John preached repentance and baptized in the name of the Lord, preparing the way for Jesus’ first advent. But the Messenger who comes “suddenly to the Temple” is Christ Himself in His second advent when He comes in power and might (Matthew 24). At that time, He will “purify the sons of Levi” (v. 3), meaning that those who exemplified the Mosaic Law would themselves need purification from sin through the blood of the Savior. Only then will they be able to offer “an offering in righteousness” because it will be the righteousness of Christ imputed to them through faith (2 Corinthians 5:21).