One God, Old and New Testaments
Tertullian, Against Marcion 4
Someone will argue that two supreme beings can coexist, distinct and separate within their own boundaries. They will cite the example of earthly kingdoms, many in number yet each supreme in its own region, and they will think human things can be compared with divine things.
If that argument is allowed, what stops us from introducing not just a third and fourth god, but as many gods as there are kings of nations? The issue concerns God, whose defining property is that he admits no comparison with any example. Nature itself declares this — if not Isaiah, then God speaking through Isaiah: "To whom will you liken me?" (Isaiah 40:18). Human things may be compared with divine things, but not with God. For God is one thing; the things of God are another.
Finally, whoever uses a king as an example of a supreme being should see that the example collapses. A king may be supreme on his own throne up to God, yet he remains beneath God; once compared to God, he ceases to be supreme, having been transferred to God. If that is so, how can you use that thing as an analogy for God when the analogy vanishes the moment it approaches the comparison? What if even among kings the supreme is not multiple but unique and singular — namely the King of kings, who, by the summit of greatness and the subjection of all other ranks, stands as the culmination of dominion?
Even kings of another sort, singular in the union of empire and presiding over what we might call minute kingdoms, if examined from every side to determine who excels in the substance and power of their realms, will inevitably yield a single summit of greatness, all lower degrees gradually excluded by the process of comparison. Thus, even when the supreme appears multiple in dispersion, it is unique in its powers, nature, and state. Accordingly, when two gods are compared as two supreme beings, the union of the supreme must concede to the other by the verdict of comparison, because the supreme consists in its own victory — having overcome another great being, not supreme — and from that defeat it possesses a solitude of singular excellence, making it unique. This inescapable logic forces the conclusion: either deny that God is the supreme being, which no wise person will accept, or refuse to share that supremacy with anyone else.
Latin
Sed argumentabitur quilibet posse et duo summa magna consistere, distincta atque disiuncta in suis finibus, et utique aduocabit exemplum regna terrarum, tanta numero et tamen summa magna in suis quibusque regionibus, et putabit ubique humana diuinis conferenda. iam ergo si huic argumentationi locus dabitur, quid prohibet, non dico et tertium et quartum deum inducere, uerum tot iam numero quot et gentium reges? de deo agitur, cuius hoc principaliter proprium est, nullius exempli capere comparationem. hoc natura ipsa, si non aliquis Esaias, uel ipse per Esaiam deus, contionabitur: cui mesimilabitis? diuinis forsitan comparabuntur humana, deo non ita. aliud enim deus, aliud quae dei. denique qui exemplo uteris regis quasi summi magni, uide ne iam non possis eo uti. rei enim, etsi summum magnum est in suo solio usque ad deum, tamen infra deum; comparatus autem ad deum excidet iam de summo magno, translato in deum. hoc si ita, quomodo uteris eius rei exemplo ad dei comparationem quae, dum ad comparationem accedit, amittitur? quid nunc, si nec inter reges plurifarium uideri potest summum magnum, sed unicum et singulare, apud eum scilicet, qui rex regum ob summitatem magnitudinis et subiectionem ceterorum graduum quasi culmen dominationis excipitur'? sed etiam [alterius formae] reges, qui singulares in unione imperii praesunt si(militer) minutalibus, ut ita dixerim, regnis, (si) undique conferantur in examinationem, qua constet, quis eorum praecellat in substantiis et uiribus regni, in unum necesse est summitas magnitudinis eliquetur, omnibus gradatim per comparationis exitum de magnitudinis summa expressis et exclusis. I adeo etsi in disperso multifarium uidetur summum magnum, suis uiribus et sua natura et suo statu unicum est. proinde cum duo dii conferuntur ut duo [reges et duo] summa magna, in alterum concedat necesse est unio summi magni ex sententia comparationis, quia summum uictoria sua constat, superato aemulo alio magno, non tamen summo, atque ex defectione, aemuli solitudinem quandam de singularitate praestantiae suae possidens unicum est. ineluctabilis iste complexus in hoc sententiam constringit: aut negandum deum esse summum magnum, quod nemo patietur sapiens, aut nulli alii communicandum.