Adversus Marcionem IV.1.10 - 11 and Irenaeus

Argument Structure	Irenaeus (AH IV.40.1 - 1)	Tertullian (Adv. Marc. IV.1.10 - 11)	Structural Significance
Polemic target: dualist separation of gods	Rejects idea of two different Fathers (one saving, one punishing).	Quid differentiam rerum ad distantiam interpretaris potestatum? (“Why do you interpret differences of things as differences of powers?”)	Same anti-Marcionite thesis: diversity ≠ different deity.
Unity of divine agency	One Father prepares both kingdom and eternal fire.	Creator performs opposite actions: percutiam… sanabo… occidam… vivificabo… faciens pacem… condens mala.	Identical logic: opposites belong to one God.
Scriptural paradox (peace vs evil)	“I am a jealous God… making peace and creating evil things.”	Explicit citation: condens mala et faciens pacem.	Same prophetic prooftext used to argue unity through opposites.
Judgment imagery supporting unity	Sheep vs goats; tares vs wheat — one judge divides humanity.	Creator’s nature expressed through antitheses inherent in creation.	Shared logic: divine differentiation occurs within single authority.
Antithesis as theological method	Same God produces contrary outcomes (reward/punishment).	antitheses exemplorum… in ipsis sensibus et affectionibus eius recognoscere.	Tertullian uses explicit philosophical language for same idea.
Creator as source of apparent contradiction	Creator prepares both peace and punishment.	Creator characterized by natural oppositions: contrarii sibi semper creatoris.	Same conceptual explanation for biblical tensions.
Cosmological analogy	Unified divine governance of diverse outcomes.	World structured by opposing substances (diversitatibus structum).	Parallel reasoning: unity through structured oppositions.
Conclusion against Marcionite dualism	Same Father behind law and gospel.	Prius debueras alium deum luminis… alium legis, alium evangelii… (refutation of dualistic split).	Same argumentative climax.

The parallel between Irenaeus and Tertullian here is not simply that both cite similar scriptural themes, but that they deploy an identical logical structure to refute Marcionite dualism. In Irenaeus’s argument the central claim is that the same God who prepares salvation also prepares judgment; therefore the apparent oppositions within Scripture — peace and punishment, mercy and severity — do not imply two different divine powers but rather the single, consistent activity of the Creator. He illustrates this by invoking prophetic paradox (“making peace and creating evil things”), by appealing to judgment imagery (sheep and goats, tares and wheat), and by insisting that diversity of outcomes arises from one divine will. Tertullian reproduces this reasoning almost step for step. His question, quid differentiam rerum ad distantiam interpretaris potestatum? directly echoes the Irenaean premise that difference in effects does not imply difference in gods. He then invokes the same paradoxical divine actions (ego percutiam et ego sanabo… condens mala et faciens pacem), framing them as examples of “antitheses” inherent in the Creator’s own nature. The argument unfolds along the same trajectory: opposites belong to one divine agent; diversity presupposes unity; therefore Marcion’s division between law and gospel collapses. What is especially significant is that the parallel lies in the structure of reasoning, not merely in shared prooftexts. Both authors move from prophetic paradox → unity of divine agency → reinterpretation of scriptural oppositions → rejection of dualist theology. Tertullian’s version reads like a rhetorical reworking that translates Irenaeus’s theological synthesis into a more formal dialectical register, emphasizing “antitheses” and philosophical categories while preserving the same argumentative skeleton. This strongly suggests that Tertullian is not independently arriving at the same conclusions but is reworking a pre-existing anti-Marcionite tradition — plausibly the lost Irenaean Adversus Marcionem — whose characteristic method was to demonstrate that the Creator Himself announced both continuity and transformation, thereby neutralizing Marcion’s claim that contradiction in Scripture requires two gods.