Yahweh Has Had Compassion On His People, For Even In The Past He Has Not Treated Israel As Badly As They Deserved (Isaiah 27:7-9).
Yahweh has not smitten His people as severely as He has smitten others, nor has He slaughtered them with the same severity. In His treatment of her (as with a wife, compare Isaiah 50:1) He will contend with her in measured fashion, by removing her (bringing about a separation with her) through one who comes from the East (Assyria) like a strong wind. And by means of this the iniquity of Jacob (Israel) will be purged. This is how He will take away his (Jacob's) sin. This last will take place when Jacob finally gets rid of all idolatry.
Analysis.
a Has He smitten him as He smote those who smote him? Or is he slain according to the slaughter of those who were slain by him? (Isaiah 27:7).
b When you send her away you contend with her in measure, He has removed her with His rough blast in the day of the east wind (Isaiah 27:8).
b Therefore by this will the iniquity of Jacob be purged, and this is all the fruit of the taking away of his sin (Isaiah 27:9 a).
a When he makes all the stones of the altar as chalkstones, crushed to pieces, so that the Asherah images and the sun-images will rise no more (Isaiah 27:9 b).
In ‘a' Yahweh has smitten His people in a measured way, and in the parallel the result must be that they in turn are to crush in pieces their idols so that they have nothing more to do with them. In ‘b' He ‘causes a separation' with His people and in the parallel the purpose is that through exile their sin will be purged.
‘Has he smitten him as he smote those who smote him?
Or is he slain according to the slaughter of those who were slain by him?'
Isaiah now points out that although Yahweh has smitten Israel, and has caused men to be slain in her, yet He has not done so to the extent that He has with her enemies. His hand has been more heavy on her enemies, smiting them severely and slaying them in large numbers (see Isaiah 37:36). But with Israel He has been much less severe. Justice has been tempered with mercy. For the identity of who did the smiting on God's behalf see Isaiah 10:20. It was the Assyrian.
‘When you send her away you contend with her in measure.
He has removed her with his rough blast in the day of the east wind.'
God's treatment of Israel has always been measured. The change to the feminine pronoun indicates that He is seeing her as similar to a wife. When He has ‘sent her away' (brought about a separation from her - compare Isaiah 50:1), that is, has had her taken away captive it has always been in reasonable proportions. Her removal has always been with the rough, but short, blast of the desert wind, so that she could soon be restored, rather than with the more constant continuing winds from other directions which would have ensured her permanent downfall. Or the ‘rough blast in the day of the east wind' might be the Assyrians coming from the east. Either way His purpose is always finally to restore her
‘Therefore by this will the iniquity of Jacob be purged,
And this is all the fruit of the taking away of his sin,
When he makes all the stones of the altar as chalkstones, crushed to pieces,
So that the Asherah images and the sun-images will rise no more.'
Thus would occur the purging of the iniquity, the inner sinfulness, of Jacob (compare Isaiah 6:7). It would be fulfilled in this measured but violent way, which would accomplish what was necessary. It would be so that she would receive the full fruit in order that her sin might be dealt with. And it would result in the taking away of Jacob/Israel's outwardly expressed sins. It would result in the crushing to pieces of the altar stones of their false gods as though they were chalkstones, removing the false altars used for the worship of the Asherah images and the sun-images, so that these false divinities would rise no more, that is, would no more be worshipped or taken heed of.
God's purpose always in allowing His people to be distressed was so that they might turn from sin and be freed from idolatry, and that is depicted as fully accomplished here. For one day Israel would be set free from the idolatry to which she was prone. Note the fact that it is ‘Jacob' not Judah that is described here. Isaiah still has in mind the whole nation.