This paper argues that Paul’s theology in the epistolary framework of Romans is shaped by Isaianic motifs, especially those found in Isaiah 52:7–53:12. While other scholars have examined Paul’s quotations and allusions, I focus on Paul’s conceptual use of Isaiah in Romans 15:14–16:27. Following the principles of inner-biblical exegesis (cf. Fishbane 1985, 281–82), I propose that the reversal of the people’s hardening is brought upon Jews and Gentiles by faith through the revelation and exposition of Paul’s gospel in Romans. That is, Isaiah’s prophecies and eschatological expectations that God’s people will see, hear, and understand his power and salvation through the herald’s proclamation of good news provide Paul with the theological substructure for the epistolary framework of Romans.
Paul’s more explicit quotations and allusions to Isaiah elsewhere in Romans confirm Isaiah’s influence on Paul’s theological framework. The only Isaianic quotation in the epistolary framework is Isa 52:15 in Rom 15:21. Paul grounds in this verse his apostolic conviction to preach where Christ has not been named. Thus, Paul further establishes the people’s restoration from obduracy to sight and Gentile inclusion as theologically informed by these Isaianic expectations. Additionally, Paul recurrently quotes and alludes especially to Isa 40–55 and 52–53 (e.g., Rom 2:24; 4:25; 8:32; 10:15–16; 13:11; 15:21). By doing this, Paul emphasizes the necessity of the gospel proclamation for people to see and respond in faith in order for the power of God to be revealed in them.
Lastly, the doxology at the end of Romans demonstrates Paul’s dependence on the prophetic Scriptures. Paul elaborates on the gospel and preaching of Jesus Christ using the motifs of mystery and revelation. Earlier in Romans, Paul alludes to Isaiah and other texts, relating mystery to God’s hardening and the subsequent salvation of “all Israel” (9:18, 11:7, 25–27; cf. Isa 27:9; 29:10; 59:20–21; Deut 29:4 [29:3 MT]; Ps 69:22–23). The gospel now reveals this mystery made known through the prophetic writings (cf. 3:21), further emphasizing the eschatological fulfillment of the gospel proclamation. The veil is lifted through the gospel, and sin is taken away. By revealing the mystery hidden for long ages, those who were not told now see, and those who have not heard now understand (Rom 15:21; cf. Isa 52:15). Such was Paul’s apostolic conviction, informed by these Isaianic motifs.