It is a long and wide task to determine the main theme of Isaiah’s book, requiring an intentional look into the particulars and the whole. Such a task often leads the student to lean on the opinions of various scholars and those who have studied the book for years, and it is by the grace of God that the student is supplied with these resources. However, this should not discourage the student from attempting to determine the main theme from the text itself. This analysis will seek to determine the main theme of Isaiah by primarily analyzing the text of the book, but the opinion of authorship will function to supply some structure to the analysis. Upon observing the book of Isaiah and Isaianic scholarship, the main theme can be identified as such: the holy God of Israel will bring the arrogant and rebellious to judgment and he will bring those who humbly trust in him to salvation.
Expanding the Main Theme
J. M. Roberts opted for a more focused main theme for Isaiah’s book, noting, “If there is any one concept central to the whole Book of Isaiah, it is the vision of Yahweh as the Holy One of Israel.” Certainly the theme of God’s holiness is central to the many themes of Isaiah’s book. However, it appears that Isaiah uses God’s holiness to develop several other themes – i.e. it would be wrong to assume that the entirety of Isaiah’s book constitutes an explicit reference to God’s holiness. For example, Isaiah 6 plays a key role in Roberts’ analysis of the main theme, where “the whole scene may be seen as an explication of what the seraphs meant when they proclaimed Yahweh as holy.” There is no question that a large part of Isaiah 6 is concerned with the grand theological claim of God’s holiness. However, to mark the whole scene as an explication of ‘Yahweh as holy’ offers a misleading limitation to the correct exegesis of the passage. The first commission of Isaiah offers more than a mere explication of Yahweh as holy, as it elucidates the proper response to such a claim. Similarly, more of Isaiah’s book as a whole focuses on how God’s people are to respond to God’s holiness than the mere explication of God’s holiness; but the explication of God’s holiness is absolutely necessary in order to focus on how God’s people are to respond to it. In other words, there is no need to separate the parts from the whole: Isaiah unfolds the necessary response to God’s holiness (humble trust or arrogant rebellion) and the consequences of that response (salvation or judgment). As Larry Taylor noted, “Isaiah’s prophecy is about God and his ways with people.” It is too limited to merely identify Isaiah’s central theme (or concept) as the ‘vision of Yahweh as the Holy One of Israel,’ but the main theme ought to be nevertheless understood in light of God’s holiness. Therefore, the main theme of Isaiah should be identified as such: the holy God of Israel will bring the arrogant and rebellious to judgment and he will bring those who humbly trust in him to salvation. Every passage and theme functions to unfold this essential theme in the book of Isaiah.
Barry G. Webb observed that the two commission passages of Isaiah play a key role in understanding two major themes in the book of Isaiah. The first commission (Isaiah 6) calls the prophet to a ministry of judgment, and the second commission (Isaiah 40) calls the prophet to a ministry of salvation. As Webb noted, these two ministries of the prophet “become the dominant notes of the first and second halves of the book.” This is not to say that judgment is only reserved for the first half of the book and salvation for the second half; but more importantly, the two themes present the great paradoxical theme (judgment and salvation, destruction and restoration) throughout the entire book of Isaiah.
Just as Roberts identified three emphases of his observed main theme of Isaiah, Webb identified three developments of these two themes (judgment and salvation) throughout the book of Isaiah. Webb’s three developments included God’s discipline of Israel, the characterization of God’s holiness, and the restoration of Israel’s missional ability to be a blessing to the nations. In the simple comparison between Roberts and Webb one will notice that generally the same themes are identified, but the distinction primarily resides in the way each understands these themes in relation to their chosen main theme. All in all, this demonstrates the need to not sacrifice the parts for the whole, where a logical and exegetical compromise of all the themes ought to emphasize Isaiah’s main theme. In light of this need, John N. Oswalt’s analysis appears best.
The Several Themes of the Main Theme
Oswalt observed, “The book of Isaiah is like a modern symphony, with themes appearing and reappearing in fascinating harmony.” One of the best methods for observing and compiling these themes is through Isaiah’s literary use of the themes. A recurring feature in the book of Isaiah is the “pairing of opposites, such as judgment and hope, servanthood and kingdom, trust and rebellion, and arrogance and humiliation.” Oswalt identified and examined seven major themes in the book of Isaiah: (1) judgment and hope, (2) servanthood and kingdom, (3) trust and rebellion, (4) arrogance and humiliation, (5) the uniqueness of Yahweh, (6) the nations, and (7) righteousness. A survey of these themes in the book of Isaiah will demonstrate that the main theme of Isaiah essentially concerns the holy God of Israel bringing the arrogant and rebellious to judgment and bringing those who humbly trust in him to salvation.
Judgment and Salvation
The interchange between the theme of judgment and salvation begins in the very first chapter of the book of Isaiah. Notice the theme of judgment in 1:1-15, 21-24, and 28-31; and notice the close pairing of this theme with that of the theme of salvation in 1:16-20 and 25-27. The oscillation between these two themes continues throughout chs. 1-5 (primarily judgment in 1:1-31, salvation in 2:1-5, an announcement of judgment in 2:6-4:1, a promise of salvation in 4:2-6, and judgment again in 5:1-30) and it continues on throughout the entirety of the book – the major emphasis of chs. 7-39 is judgment, and the main emphasis of chs. 40-66 is salvation.
The purpose of this oscillation or interchange between judgment and salvation is more than a mere literary device; it serves to make a soteriological point – i.e. hope and salvation for the rebellious nation of Israel can only come through judgment. As Webb recognized, “the order is significant: paradoxically, salvation emerges out of judgment and is possible only because of it.” Isaiah revealed that hope for Israel did not consist in the avoidance of judgment, but rather hope will be found through judgment. Similar to the necessary purging that Isaiah himself experienced in his first commission (ch. 6), Israel’s equipping to be a blessing to the nations first required an experience of God’s purging. Further, even for those who read the book of Isaiah post-exile – i.e. those who have experienced the glimpse of God’s restoration – the thematic interchange between judgment and hope reinforces the need to continue seeking, believing, trusting, and obeying God. Just as judgment came to those in Israel who were given the promise of hope and were yet hypocritical, prideful, and living in wickedness and sin, the postexilic Israelite must also continue to repent and seek God. Future hope and present favor do not quell one’s responsibility to live righteously.
Servanthood and Kingdom
Another thematic pairing of opposites that Isaiah emphasized was that of servanthood and kingdom. In chs. 7-12 Judah was being oppressed by the nations, and they were overpowered. The natural resolution appeared to be a strong king and ruler who could overpower the dominance of the foreign nations; but instead Isaiah offers a child (9:6). God’s resolution for the overpowered nation is the “servant-king” (cf. 9:6; 11:9; 16:5; 32:1-5; 65:25). The image of the servant-king is continued throughout the entire book of Isaiah. In chs. 7-39 Isaiah contrasted Ahaz and Hezekiah, showing how the king that submits to God with a heart of service will bring forth God’s deliverance for himself and his people. Continuing to chs. 40-55, the notable ‘Servant of the Lord’ is described with the same function as the Messiah in chs. 9-11; 16 and 32 – i.e. the redeemer of Israel will restore the nation, and he will do this by becoming a servant. The final chs. 56-66 of the book of Isaiah describe the Servant’s role as a mighty Warrior (59:15b-21; 63:1-6), functioning to make the people ‘oaks of righteousness’ (61:3). The pairing is evident: he is messiah, but he is a servant; and he is a warrior, but again he is the Spirit-anointed Servant (61:1-3).
Trust and Rebellion
Alongside the general theme of judgment in chs. 7-39, there is also the general theme of trust; and alongside the general theme of salvation is chs. 40-66, there is also the general theme of rebellion. Judgment and salvation are in themselves paired as opposites, but even those themes in their particular sections are paired with opposites – judgment with trust and salvation with rebellion. The contrast of trust and rebellion are presented in the very first chapter of Isaiah’s book (1:2, 5, 19-20, 23, 28), and the theme of trust is continued throughout the first half of the book. Chs. 7-39 function to show the ultimate trustworthiness of God in light of the empty and rebellious trust in the nations; and the picture of God’s trustworthiness culminates in the picture of God’s deliverance (12:3). However, despite God’s trustworthiness seen in his deliverance, people still rebel against him, which becomes the emphasis of the later half of Isaiah’s book (cf. the twenty references to rebellion in chs. 40-66). The later half concludes with a similar contrast noted in the beginning of the book: “surrendering to the Creator-Redeemer in trust is the height of wisdom, whereas rebellion against him is the height of folly.” The foundational theme of judgment and salvation is suited with the necessary action that determines the holy God’s judgment.
Arrogance and Humiliation
Adding to this teaching regarding the proper response to the holy God, the action of trust is equipped with the attitude of humility. By contrast, the attitude of arrogance is linked with the action of rebellion. The most powerful elucidation of this pairing of themes is found in 2:6-4:1, but it continues throughout Isaiah’s book (41:24; 44:9), being closely paired with the previous pairing between servanthood and kingdom (52:13; 57:15), and reaching its climax in chs. 56-66.
The Uniqueness of Yahweh
Similar to Roberts’ emphasis on the holiness of God in the book of Isaiah, Oswalt commented, “No book in the Bible treats [the uniqueness of Yahweh] as forcefully as does Isaiah.” Oswalt recognized the significance of God’s holiness in the book of Isaiah (ch. 6), but he also rightfully recognized that it functions as a theological theme in the background of the main theme of Isaiah’s book. Nonetheless, without the holiness of Yahweh, all other themes would be incoherent, and thus it is important to recognize its value to the main theme of Isaiah’s book. This theme is scattered throughout the entire book: Isaiah 2 makes the claim that it is only God that is deserving of worship; idols are written off as unworthy of worship (e.g. ch. 19); God often challenges false gods to prove their worthiness all throughout chs. 7-39 (especially chs. 24-27); and the claims of the several other themes often work off this understanding that it is only in God that one can humbly trust to be saved.
Another theme that unfolds the judgment and salvation of the holy God in light of the people’s humble trust or arrogant rebellion concerns the universal perspective of Israel’s salvation. The theme of the nations in Isaiah recognized Israel’s responsibility to be a blessing to the nations (cf. Genesis 12:1-9). As such, the restoration of Israel also had universal implications. This universal perspective is emphasized in both the opening and closing portions of Isaiah’s book (ch. 2 and 66), and is a continual focus throughout the entirety of Isaiah’s book (e.g., chs. 13-23; 25:6-9 [cf. 12:1-3]; ch. 47; 60:14). All in all, this theme demonstrates an important implication for Isaiah’s overall theme – i.e. God’s salvation of those who humbly trust in him and his judgment of those who arrogantly rebel against him is the universal response of the holy God to all people, not just Israel.
A lexical study of the term ‘righteous’ in the book of Isaiah makes it overwhelmingly clear that it is an important theme for the book, appearing over sixty times. While the term is evenly spread throughout the entire book, it is given special emphasis in 1:21-27 and chs. 32-33. In those passages in the first half of Isaiah’s book, the prophet emphasizes the transformational righteousness that is necessary to appease the holy God (e.g. 33:14-16). However, it is apparent that the people have not lived up to this standard and in fact cannot live up to this standard. Therefore, shifting to the next section, chs. 40-55 focus on the righteousness of God, essentially teaching that God saves for his righteousness’ sake and that the people’s righteousness will come through God’s righteousness. More specifically, God’s righteousness will become the people’s righteousness in the Servant (53:11). In the last section of Isaiah’s book, the righteous standard and God’s righteousness are blended together to resolve the obvious dilemma (56:3-9, 15a; 63:7-65:16; also not the chiastic structure in chs. 56-66). This theme of righteousness functions to clarify the main theme and its implications: “those who humbly admit their helplessness and cast themselves on the provision of God in Christ will be able to live the kind of life God requires.”
A holistic look at Isaiah’s book requires its main theme to be broadly understood, incorporating all of its parts into its one coherent theological teaching. Having analyzed the several themes emphasized in Isaiah’s book, the main and essential theme appears to be the teaching that the holy God of Israel will lead arrogant rebels to judgment and those who humbly trust in him to salvation. The many necessary implications of this main theme is expressed in the elucidation of God’s uniqueness (holiness), the universal perspective of God’s salvation unto the nations, and the concept of righteousness.
 J. J. M. Roberts, “Isaiah in Old Testament Theology,” Interpretation 36, no. 2 (April 1, 1982), 131.
 Ibid., 132.
 Larry M. Taylor, “The Holy One of Israel is Savior: Theological Themes in Isaiah,” Southwestern Journal of Theology 34, no. 1 (Fall 1991), 16.
 Barry G. Webb, The Message of Isaiah, BST (Downers Grove, IL: InterVarsity Press, 1996), 31.
 Roberts, “Isaiah in Old Testament Theology,” noted three emphases regarding his central theme: Yahweh alone is Lord (133-134), the moral dimension of God’s holiness (134-136), and the Holy One ‘of Israel’ (136-142).
 John N. Oswalt, Isaiah, NIVAC (Grand Rapids, MI: Zondervan, 2003), 41
 Ibid., 42.
 Ibid., 41-55. Also see John N. Oswalt, “Key Themes in the Book of Isaiah: Their Relevance for Christian Theology,” in The Newell Lectureships, ed. T. Dwyer (Anderson, IN: Warner, 1996), 3:13-90, 202-211.
 See Oswalt, Isaiah, 42-43.
 Webb, The Message of Isaiah, 31.
 Oswalt, Isaiah, 45.
 See the twenty references to rebellion in ibid., 48.
 Ibid., 48.
 Ibid., 49.
 For an elucidation of the chiasm in chs. 55-66, see ibid., 55.
 Ibid., 54.