The prophecy of Malachi deals with the people brought back from the captivity of Babylon, and is most important as shewing the moral condition of the people consequent upon their return. Its last verses evidently close the testimony of Jehovah to the people, till the coming of him who should prepare the way of Jehovah, in a word, till John the Baptist. The law and the prophets were until John, and Malachi is professedly, and from the nature of his testimony, the last.
The great moral principle unfolded in the book, is the insensibility of the people to that which Jehovah was for them, and to their own iniquity with respect to Jehovah-their want of reverence for God, their despisal of Jehovah. Alas! this insensibility had reached such a point that, when the very actions that proved their contempt were laid before their consciences, they saw no harm in them. Nevertheless this did not alter the purposes and counsels of God, although it brought judgment on those who were guilty of it (see chap. 1: 2, 6; 2: 14; 3: 7, 13).
Malachi also distinguishes the remnant and that which characterised them, while proclaiming the punishment of the wicked, and the call of God to those who had ears to hear to bring them back to repentance-a ministry which would restore moral order in the hearts of parents and children-that relationship, from the maintenance and exercise of which, all earthly peaceful order according to God flows; and that order is what God is considering here.
At the commencement of the prophecy Jehovah sets forth His love to Israel , slighted alas! by an ungrateful people, yet proved by their election from the beginning. Even while exhibiting the sad ingratitude of the people, Jehovah adheres to His own thoughts toward them. He will bless Israel , and He will judge Edom , in spite of the pride of the latter.
The sin of Israel , and their offensive indifference in the service of their God, is shewn (v. 6-10). This gives occasion to another expression of grace-the revelation of the name of Jehovah among all nations. Thus, the election of Israel , and mercy towards the Gentiles, are established amidst, and even on occasion of, the sin of the restored people. Verses 12-14 also display their offences against Jehovah and their contempt of His majesty. Chapter 2: 1-9 proclaims the fallen condition of the priests, who ought to have been the faithful depositaries of the mind and ways of God; verses 10-12, their misconduct towards their brethren, and their intimate relationship with idolaters, are pointed out; verses 13-16, the lightness with which they were in the habit of divorcing at their pleasure. But Jehovah was coming.
Here again we find the Lord's  first coming connected with the full result of the second. John the Baptist is announced as His messenger to prepare the way before Him; and then, the Angel of the covenant, whom they so earnestly desired, should come; but it would be in judgment, to purge the people and take away all their dross. Then should their offering in Jerusalem be acceptable to Jehovah, an offering in righteousness. But all the evil-doers should be judged; for God was unchangeable, both in righteousness and grace. It was this which, after all, secured the existence of Israel, happen what might. Let Israel then return unto Jehovah, and Jehovah would return unto them. But the pride of Israel is excited by this, and they say, "Wherein shall we return?" Their sins with respect to the offerings and the ordinances are then shewn. But grace again displays itself in prospect of the people's return from their practical alienation from God. They had but to return and prove the goodness of God.
In the midst of the pride of the wicked in their apparent success, the remnant are distinguished as being drawn together by their common spiritual wants and feelings, founded on the fear of Jehovah which governed them all. In their affliction they spake often one to another of these things;  and Jehovah hearkened and heard and wrote it down in His book. And they shall be His in the day when He maketh up His jewels. After this they should discern between the righteous and the wicked, between those that served God and those that served Him not. For the day was coming which should burn as an oven, and the proud and the wicked should be as stubble. But to those that feared the name of Jehovah, the Sun of Righteousness should rise. It should be no longer the sorrowful night of darkness and affliction and of the enemy's dominion, but a day which God would cause to shine by the presence of His Son, by the reign of His Beloved One on the earth. The righteous would have dominion over them in the morning, for the time is a time of judgment, and the wicked would be as ashes under the soles of their feet.
It will be remarked here, that all is in connection with the authority of Jehovah and His dispensations towards Israel, and with the conduct of Israel, as a nation, towards their God. That which belongs to the first coming of Christ, and its consequences to Israel, is not brought in here. John the Baptist is presented as the forerunner of Jehovah, who without doubt is Christ Himself, but who here comes as the Angel of the covenant, coming suddenly to His temple, and trying everything in Israel by fire and by His judgment, in order that the offering of Judah may be pleasant to Jehovah as in the days of old. The transgressions here spoken of are those of the people brought back from Babylon against Jehovah. The Gentiles, and their empire, are not seen here. All takes place between Israel only and Jehovah, the God of their fathers, as in former days between the people loved of God and Jehovah who loved them. A strange god is that which Jehovah will not endure. It is Levi, with whom His covenant had been; it was the priests, whose lips should have kept the true knowledge of Jehovah.
There is even no king here spoken of; except that Jehovah, whose name is terrible among the heathen, is their king. Finally the people (Israel) are commanded to return to the law of Moses given at Horeb for all Israel.
Thus we have here Jehovah's unchangeable love for the people whom He gathered to Himself at Horeb, His controversy with them on account of their sins, the marking out of a faithful remnant, and the sending of a messenger before the execution of the judgment. Israel is looked at nationally, in their own relationship with Jehovah, as returned from captivity and awaiting the judgment of their God, who sends His messenger to forewarn them.
All was prepared to put the people morally to the proof, with respect to the accomplishment of this, at the time when John the Baptist was sent; but Israel had not ears to hear, and all was lost.
The perfect and entire fulfilment will take place at the end, after that other glorious work of God with regard to the assembly shall have been accomplished.
The longsuffering of God towards Israel had been great; for, when they had rejected His Son, He sent them-through the intercession of that same well- beloved Saviour on the cross-the message by the mouth of Peter, that, if they repented, the Christ whom they had slain would return. But their leaders were more than deaf to this grace on the part of God, and their house still remains empty and desolate.
At the time of the end, Elias-whose mission was to call back an apostate Israel who had forsaken Jehovah to own Him in truth, and that, by the sovereign grace of God, although in connection with the law, and that Mount Horeb, whither he went to lay down the burden of his prophetic office, when rendered useless by the unbelief of the people-Elias shall effectually accomplish his mission before the great and terrible day of Jehovah; in order that the curse of God may not fall upon the land of His delight in that day when He will definitively execute His judgments. It is on this account that John the Baptist is spoken of as being Elias, if Israel could receive it; for he answered to verse 1 of chapter 3, whilst, at the same time, he said he was not Elias; for in fact he did not at all fulfil verses 5, 6 of chapter 4 (compare Luke 1: 17, 76).
The prophecy speaks to the conscience of those who lived at the time it was delivered (chap. 3: 10); and passes on-shewing that at the end of those times Israel would be put on trial by the mission of grace-to the last days, in which God would display His unchangeable love for His people, and His righteous judgment against evil, by separating a remnant unto Himself for blessing, and by executing judgment on the rebellious.
The Gentiles are not mentioned, nor even the connection of His people with Christ, coming down as man to the earth.
We have thus in these three post-captivity prophets, three distinct subjects, but which make a whole of the three. In Haggai it is grace toward the returned remnant, God's Spirit still among them, and in connection with the house and worship of Jehovah, the temple. Its latter glory should be greater than its former. The kingdoms of the heathen should be cast down, and Zerubbabel (Christ) as a signet on Jehovah's hand. Peace would be given in Jerusalem.
Zechariah takes up two points: first the empires of the heathen and God's providential ways with Israel-the times of the Gentiles-Jerusalem is owned, but judged of God and stamped as Babylonish in its true character; but at the end the Branch, the Lord Jesus, sets crowns instead of fasting for the faithful- Babylon being already judged-and strangers should come and build in the temple of the Lord.
From chapter 7 to the end, it is the relation of Israel with Christ, and His rejection and its consequences in the last judgment of Jerusalem ; but for all that Jehovah, as we have often seen, would judge definitively all the nations assembled against her. The remnant would be brought to repentance, and Jerusalem be holiness to the Lord, nor should strangers defile it.
Finally we have Malachi shewing us, the state the Jews soon got into, slighting all that was agreeable to God, and indifferent and insensible to their violating every righteous feeling; the practical separation of those that feared the Lord, and the coming of the Lord in judgment and deliverance: meanwhile their recall to the authority of the law, and the coming of Elias before the great and terrible day of the Lord, to turn their hearts in grace into the way of peace.
 It is, note distinctly, Jehovah's.
 See the lovely picture of this in the first two chapters of Luke's Gospel, before he begins the general subject of it. Only then the Saviour was rejected, and the remnant passed into the assembly, the deliverance of Israel being deferred to the coming of the Lord in power. Here it is looked at as the remnant in Israel connected with that deliverance.