In Romans 10:9, the apostle Paul writes:
If you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved.
In my book, I argue that when Paul refers to the “mouth” alongside the “heart” as an instrument of salvation in Romans 10:8-10, he is not merely making an incidental aside or rhetorical flourish. Rather, the “mouth” is a key to Paul’s argument about the nature of salvation. Salvation is not by law, but by the gospel, which is a specific message about a specific person. This message is not something to do, but something to be believed and spoken. Therefore salvation comes by the heart and the mouth.
In Rom 10:9–10, Paul elaborates further on the scriptural testimony to the twofold locus of the message: “in the mouth” and “in the heart” (cf. Rom 10:8). He shows that this reference is not merely an incidental hendiadys, but rather is a significant pointer to a twofold means of receiving the message of salvation (Rom 10:9–10). Paul expounds his understanding of salvation in terms both of believing and of speaking. Salvation comes through confession of Jesus as Lord alongside faith in God’s resurrecting power—in contrast to any human attempt at resurrection (cf. Rom 10:7). Thus believing and speaking are, for Paul, two sides of the same soteriological coin. “Speech” is thus a fundamental mode of Israel’s response to the Law. In fact, the idea of the “mouth” as a locus of eschatological salvation is a significant motif in at least two other scriptural contexts from which Paul cites in Rom 9 – 11. The Song of Moses in Deut 32 (v. 21 is cited in Rom 10:19) makes much of Israel’s “mouth” (στόμα). It is introduced as a song which is to appear on the “mouth” of Israel and Israel’s “seed” (Deut 31:19, 21). All Israel is thus commanded to take on the prophetic role of Moses, whose “mouth” speaks to the entire creation (Deut 32:1; cf. Deut 18:18). The content of Israel’s prophetic song is God’s salvation, a salvation that he achieves in spite of—indeed, because of—Israel’s own failure to keep the Law. The goal of the song is to bring the nations to rejoice in God’s salvific power, alongside Israel (Deut 32:43 LXX, cited in Rom 15:10; cf. the “one mouth” of Rom 15:6). The eschatological “covenant” of Isa 59:21 (cited in Rom 11:27a), also employs these concepts and terminology. In light of Israel’s flagrant Law-breaking and their subsequent unfitness to achieve God’s purposes in the world, God himself saves Israel (Isa 59:15–16) and places his “words” (ῥήματα) on Israel’s “mouth” and on the “mouth” of their “seed” forever (Isa 59:21). (pp. 218-219)
The full details of the argument and further references may be found in chapter 6 of the book (pp. 216-219). The chapter is available from the publisher in electronic format:
Windsor, Lionel J. Paul and the Vocation of Israel: How Paul’s Jewish Identity Informs his Apostolic Ministry, with Special Reference to Romans. BZNW 205. Berlin / Boston: Walter de Gruyter, 2014.