| Irenaeus (IV.34 directed against Marcion IV.34.1) | Tertullian (IV.1 directed against Marcion) | Scriptural source |
|---|---|---|
| “Out of Zion shall go forth the law and the word of the Lord from Jerusalem… they shall beat their swords into ploughshares.” | “Out of Zion shall go forth the law and the word of the Lord from Jerusalem… He shall judge among the nations.” | Isaiah 2:3–4 |
| “A new law has gone forth from the Lord over the whole earth.” | “Another law and another word — the gospel and apostolic proclamation.” | Isaianic ‘new law’ motif (Isa 2; Isa 51:4) |
| “The prophets foretold the conduct, doctrine, and sufferings of the Lord.” | “Isaiah long ago declared these things.” | Prophetic fulfillment framework |
| “Not another God, but the same one who spoke through the prophets.” | “Difference of dispensation but one and the same God.” | Anti-Marcionite monotheistic argument |
| “The new covenant comes from the Lord’s advent.” | “A new order under Christ.” | New covenant theology |
| “The word goes out to the nations.” | “Judgment/light for the nations.” | Isa 51:4; universal mission |
| “The law brings peace.” | “Swords into ploughshares… minds transformed.” | Isaiah 2 ethical transformation |
In Irenaeus the relevant passage appears in Adversus Haereses III (especially III.12–13 context). He argues that the “new covenant” does not imply a different God but the fulfillment of prophetic expectation, and he cites Isaiah: “For out of Zion shall go forth the law, and the word of the Lord from Jerusalem; and he shall rebuke many peoples, and they shall beat their swords into ploughshares…” (Isaiah 2:3–4). The point is that the prophets already announced a future law proceeding universally from Jerusalem, proving continuity between Mosaic revelation and the Gospel.
Tertullian makes essentially the same move in Adversus Marcionem IV.1 (and surrounding opening chapters). Responding to Marcion’s division between Law and Gospel, he appeals to Isaiah: “Ex Sion exibit lex et verbum Domini ex Jerusalem… iudicabit inter nationes…” (“Out of Zion shall go forth the law and the word of the Lord from Jerusalem… he shall judge among the nations”). He explicitly interprets this as referring to “another law” and “another word,” meaning the Gospel and apostolic preaching, yet insists this diversity belongs to one and the same God who arranged and foretold both dispensations.
So the sameness lies in three things. Both authors cite the same Isaianic oracle (Isaiah 2:3–4, often combined with Isa 51:4 themes). Both use it against Marcionite dualism to argue that the Gospel was predicted within the prophetic tradition. And both interpret the “new law” going forth from Zion not as evidence of a new deity but as the fulfillment of a prophetic development already announced by the Creator’s prophets.
