This passage falls into three parts, -- the 'stout words' against God which the Prophet sets himself to confute (verses 13-15); the prophecy of the day which will show their falsehood (verse 16 to iv.3); and the closing exhortation and prediction (iv.4-6).
I. The returning exiles had not had the prosperity which they had hoped. So many of them, even of those who had served God, began to let doubts darken their trust, and to listen to the whispers of their own hearts, reinforced by the mutterings of others, and to ask: 'What is the use of religion? Does it make any difference to a man's condition?' Here had they been keeping God's charge, and going in black garments 'before the Lord,' in token of penitence, and no good had come to them, while arrogant neglect of His commandments did not seem to hinder happiness, and 'they that work wickedness are built up.' Sinful lives appeared to have a firm foundation, and to rise high and palace-like, while righteous ones were like huts. Goodness seemed to spell ruin.
What was wrong in these 'stout words'? It was wrong to attach such worth to external acts of devotion, as if these were deserving of reward. It was wrong to suspend the duty of worship on the prosperity resulting from it, and to seek 'profit' from 'keeping his charge.' Such religion was shallow and selfish, and had the evils of the later Pharisaism in germ in it. It was wrong to yield to the doubts which the apparently unequal distribution of worldly prosperity stirred in their hearts. But the doubts themselves were almost certain to press on Old Testament believers, as well as on Old Testament scoffers, especially under the circumstances of Malachi's time. The fuller light of Christianity has eased their pressure, but not removed it, and we have all had to face them, both when our own hearts have ached with sorrow and when pondering on the perplexities of this confused world. We look around, and, like the psalmist, see 'the prosperity of the wicked,' and, like him, have to confess that our 'steps had wellnigh slipped' at the sight. The old, old question is ever starting up. 'Doth God know?' The mystery of suffering and the mystery of its distribution, the apparent utter want of connection between righteousness and well-being, are still formidable difficulties in the way of believing in a loving, all-knowing, and all-powerful God, and are stock arguments of the unbeliever and perplexities of humble faith. Never to have felt the force of the difficulty is not so much the sign of steadfast faith as of scant reflection. To yield to it, and still more, to let it drive us to cast religion aside, is not merely folly, but sin. So thinks Malachi.
II. To the stout words of the doubters is opposed the conversation of the godly. 'Then they that feared the Lord spake one with another,' nourishing their faith by believing speech with like-minded. The more the truths by which we believe are contradicted, the more should we commune with fellow-believers. Attempts to rob us should make us hold our treasure the faster. Bold avowal of the faith is especially called for when many potent voices deny it. And, whoever does not hear, God hears. Faithful words may seem lost, but they and every faithful act are written in His remembrance and will be recompensed one day. If our names and acts are written there, we may well be content to accept scanty measures of earthly good, and not be 'envious of the foolish' in their prosperity.
Malachi's answer to the doubters leaves all other considerations which might remove the difficulty unmentioned, and fixes on the one, the prophecy of a future which will show that it is not all the same whether a man is good or bad. It was said of an English statesman that he called a new world into existence to redress the balance of the old, and that is what the Prophet does. Christianity has taught us many other ways of meeting the doubters' difficulty, but the sheet anchor of faith in that storm is the unconquerable assurance that a day comes when the righteousness of providence will be vindicated, and the eternal difference between good and evil manifested in the fates of men. The Prophet is declaring what will be a fact one day, but he does not know when. Probably he never asked himself whether 'the day of the Lord' was near or far off, to dawn on earth or to lie beyond mortal life. But this he knew -- that God was righteous, and that sometime and somewhere character would settle destiny, and even outwardly it would be good to be good. He first declares this conviction in general terms, and then passes on to a magnificent and terrible picture of that great day.
The promise, which lay at the foundation of Israel's national existence, included the recognition of it as 'a peculiar treasure unto Me above all people,' and Malachi looks forward to that day as the epoch when God will show by His acts how precious the righteous are in His sight. Not the whole Israel, but the righteous among them, are the heirs of the old promise. It is an anticipation of the teaching that 'they are not all Israel which are of Israel,' And it bids us look for the fulfilment of every promise of God's to that great day of the Lord which lies still before us all, when the gulf between the righteous and the wicked shall be solemnly visible, wide, and profound. There have been many 'days which I make' in the world's history, and in a measure each of them has re-established the apparently tottering truth that there is a God who judgeth in the earth, but the day of days is yet to come.
No grander vision of judgment exists than Malachi's picture of 'the day,' lurid, on the one hand, with the fierce flame, before which the wicked are as stubble that crackles for a moment and then is grey ashes, or as a tree in a forest fire, which stands for a little while, a pillar of flame, and then falls with a crash, shaking the woods; and on the otherhand, radiant with the early beams of healing sunshine, in whose sweet morning light the cattle, let out from their pent-up stalls, gambol in glee. But let us not forget while we admire the noble poetry of its form that this is God's oracle, nor that we have each to settle for ourselves whether that day shall be for us a furnace to destroy or a sun to cheer and enlighten.
We can only note in a sentence the recurrence in verse 1 of the phrases 'the proud' and they 'that work wickedness,' from verse 15 of chapter iii. The end of those whom the world called happy, and who seemed stable and elevated, is to be as stubble before the fire. We must also point out that 'the sun of righteousness' means the sun which is righteousness, and is not a designation of the Messiah. Nor can we dwell on the picture of the righteous treading down the wicked, which seems to prolong the previous metaphor of the leaping young cattle. Then shall 'the upright have dominion over them in the morning.'
III. The final exhortation and promise point backwards and forwards, summing up duty in obedience to the law, and fixing hope on a future reappearance of the leader of the prophets. Moses and Elijah are the two giant figures which dominate the history of Israel. Law and prophecy are the two forms in which God spoke to the fathers. The former is of perpetual obligation, the latter will flash up again in power on the threshold of the day. Jesus has interpreted this closing word for us. John came 'in the spirit and power of Elijah,' and the purpose of his coming was to 'turn the hearts of the fathers to the children' (Luke i.16, 17); that is, to bring back the devout dispositions of the patriarchs to the existing generations, and so to bring the 'hearts of the children to their fathers,' as united with them in devout obedience. If John's mission had succeeded, the 'curse' which smote Israel would have been stayed. God has done all that He can do to keep us from being consumed by the fire of that day. The Incarnation, Life, and Death of Jesus Christ made a day of the Lord which has the twofold character of that in Malachi's vision, for He is a 'saviour of life unto life' or 'of death unto death,' and must be one or other to us. But another day of the Lord is still to come, and for each of us it will come burning as a furnace or bright as sunrise. Then the universe shall 'discern between the righteous and the wicked, between him that serveth God and him that serveth Him not.'