The operative verb here in Isa 52:9 is גָּאַל (ga'al) = redeem, or act as a kinsman-redeemer. The word features prominently in the story of Ruth 2:20, 3:9, 12, 13, 4:1, 3, 4, 6, 8, 14.
BDB defines this verb as: "redeem, act as a kinsman", ie, in:
- redeeming from bondage, Lev 25:48, 49
- redeeming a field, Lev 25:26, Ruth 4:46 (see above)
- claim as a kinsman, Job 3:5
However, in Isa 52:9 we have the LORD acting as the Kinsman-Redeemer. The language here appears to allude to its earliest uses in the Torah:
- Gen 48:16 [Jacob speaking] the angel who has redeemed me from all harm—may He bless these boys. And may they be called by my name and the names of my fathers Abraham and Isaac, and may they grow into a multitude upon the earth.”
- Ex 6:6 - Therefore tell the Israelites: ‘I am the LORD, and I will bring you out from under the yoke of the Egyptians and deliver you from their bondage. I will redeem you with an outstretched arm and with mighty acts of judgment.
- Ex 15:13 - [part of the song of Moses praising God] With loving devotion You will lead the people You [the LORD] have redeemed; with Your strength You will guide them to Your holy dwelling.
The OT frequently speaks of the LORD being the One and only Redeemer of His people:
- Isa 43:1, 14 - Now this is what the LORD says— He who created you, O Jacob, and He who formed you, O Israel: “Do not fear, for I have redeemed you; I have called you by your name; you are Mine! ... Thus says the LORD your Redeemer, the Holy One of Israel: “For your sake, I will send to Babylon and bring them all as fugitives, even the Chaldeans, in the ships in which they rejoice. ... Thus says the LORD, your Redeemer who formed you from the womb: “I am the LORD, who has made all things, who alone stretched out the heavens, who by Myself spread out the earth,
- Jer 50:34 - Their Redeemer is strong; the LORD of Hosts is His name. He will fervently plead their case so that He may bring rest to the earth, but turmoil to those who live in Babylon.
- Ps 130: 7, 8 - O Israel, put your hope in the LORD, for with the LORD is loving devotion, and with Him is redemption in abundance. And He will redeem Israel from all iniquity.
Note that the Jews of Jesus' time were expecting Jesus to be that Redeemer (mistakenly, in a political sense) as recorded in Luke 24:21 -
But we were hoping He was the One who would redeem Israel. And besides
all this, it is the third day since these things took place.
In Isa 52:9, the LORD promises to redeem again [after redeeming from Egypt] for Judah and Jerusalem following the Babylonian captivity. The NT appears to allude to Messiah, Jesus, as the גָּאַל (ga'al) = kinsman-redeemer:
- Gal 3:13 - Christ redeemed us from the curse of the Law, having become a curse for us--for it has been written: "Cursed is everyone hanging on a tree"--
- Gal 4:5 - that He [Jesus] might redeem those under the Law, so that we might receive the divine adoption as sons.
- Titus 2:14 - [Jesus] who gave Himself for us, that He might redeem us from all lawlessness and might purify to Himself a people specially chosen, zealous of good works.
- 1 Peter 1:18 - knowing that you were redeemed from your futile manner of life handed down from your fathers, not by perishable things--by silver or by gold
- Rev 5:9 - And they are singing a new song, saying, "Worthy are You [the Lamb, Jesus] to take the scroll and to open its seals, because You were slain, and You purchased [ie, redeemed] to God by Your blood, out of every tribe and tongue and people and nation,
Jesus is uniquely qualified to redeem sinners, ie, act as the kinsman-redeemer, because the NT portrays Jesus as "our brother", Heb 2:11-13, 17, Ps 22:22, Isa 8:17, 18, Matt 12:48, 49, John 20:17, Rom 8:29.
Thus, Isa 52:9 is a pivotal text which points back to the LORD being Israel's (and Jerusalem's) redeemer, as well as forward to the coming Messiah as Israel's redeemer. See Luke 24:21 as quoted above.
In Isa 52:9, "Jerusalem" stands for all the Jews, ie, Judah, and by extension, all Israel. See Ezra 1:1-4.