My question was always what does this mean and why would Celsus say it:
Surely it is intolerable for you to say, that if our present rulers, on embracing your opinions, are taken by the enemy (or 'are overcome, defeated, conquered'), you will still be able to persuade those who rule after them; and after these have been taken (or 'are overcome, defeated, conquered'), you will persuade their successors and so on, until at length, when all who have yielded to your persuasion have been taken some prudent ruler shall arise, with a foresight of what is impending, and he will destroy you all utterly before he himself perishes.
This seems like such a strange argument when you think about it. Is Celsus just referencing Christian appeals to the Emperor (a la Justin Martyr)? The more I think about it the less likely that actually seems. The Christians apparently convinced an Emperor to embrace their opinions. This has to be considered to be the historical context. This Emperor must have 'been conquered' here is the Liddell entry:
ἁλίσκομαι [α^λ], defect. Pass., Act. supplied by αἱρέω (
A. [select] “ἁλίσκω” Aq. Ps.21(22).14, cf. “ἐλέφας μῦν οὐχ ἁλίσκει” Zen.3.67): impf. ἡλισκόμην (never ἑαλ-) Hdt., etc.: fut. “ἁλώσομαι” Hdt., etc., later “ἁλωθήσομαι” LXX Ez.21.24 (19) cod. A: aor. (the only tense used by Hom.) “ἥλων” Od.22.230, always in Hdt., and sometimes in codd. of Att., as Pl. Hp.Ma. 286a, Hyp.Eux.15, cf. X.An.4.4.21, but the common Att. form was “ἑάλων” IG2.38, etc., cf. Thom.Mag.146 [α_, Ar.V.355, later α^ AP7.114 (D.L.), 11.155 (Lucill.); α^ in other moods, exc. part. “ἁλόντε” Il.5.487, inf., v. infr.]; subj. “ἁλῶ, ῷς, ῷ” A.Th.257, E.Hipp. 420, Ar.Ach.662, V.898, etc., Ion. “ἁλώω” Il.11.405, “ἁλώῃ” 14.81, Hdt. 4.127; opt. “ἁλοίην” Il.22.253, Antipho 5.59, etc., Ep. 3sg. ἁλῴη (v.l. ἁλοίη, which is to be preferred) Il.17.506, Od.15.300; inf. ἁλῶναι [α^] Il.21.281, [α_] Hippon.74, s.v.l., Ep. “ἁλώμεναι” Il.21.495; part. “ἁλούς” Il.2.374, etc.; later, inf. ἁλωθῆναι v.l. in LXX Ez.40.1, D.S.21.6: pf. “ἥλωκα” Hdt.1.83, Antiph.204.7, Xenarch.7.17, Hyp.Phil.11, D. 21.105; part. “ἁλωκότα” Pi.P.3,57; ἑάλωκα [α^λ] A.Ag.30, Hdt. 1.191, 209 codd., and Att., as Th.3.29, Pl.Ap.38d, D.19.179: plpf. “ἡλώκειν” Hdt.1.84, X.An.5.2.8.: (ϝαλ-, cf. “ϝαλίσσκηται” IG9(2).1226 (Thess.), ϝαλόντοις ib.5(2).351.7 (Stymphalus)):—to be taken, conquered, fall into an enemy's hand, of persons and places, Il.2.374, etc.; ἁλώσεται (sc. ὁ Κρέων) S.OC1065; ἁλίσκεσθαι εἰς πολεμίους to fall into the hands of the enemy, Pl.R.468a, IG12(7).5 (Amorg.); “ἐν τοιαύταις ξυμφοραῖς” Pl.Cri.43c.
2. [select] to be caught, seized, of persons and things, θανάτῳ ἁλῶναι to be seized by death, die, Il.21.281, Od.5.312; without θανάτῳ, Il.12.172, Od.18.265, etc.; ἄνδρ᾽ ἐκ θνάτου κομίσαι ἤδη ἁλωκότα (sc. νόσῳ) Pi.P.3.57; γράμματα ἑάλωσαν εἰς Ἀθήνας letters were seized and taken to Athens, X.HG1.1.23; τοῖς αὑτῶν πτεροῖς ἁλισκόμεσθα, of eagle, i.e. by a feathered arrow, A.Fr.139:—to be taken or caught in hunting, Il.5.487, X.An.5.3.10:—ἁ. ἀπάταις, μανίᾳ, S.El.125, Aj.216; “ὑπ᾽ ἔρωτος” Pl.Phdr.252c; “ὑπὸνουσήματος τεταρταίου” Hp.Nat.Hom.15; “νοσήματι” Arist.Pr.954a35, etc.; μιᾷ νίκῃ ἁλίσκονται by one victory they are ruined, Th.1.121: abs., to be overcome, A.Eu.67, S.Aj.648.
3. [select] in good sense, to be won. achieved, S.OT542, E.Alc.786, X.Cyn.12.21.
4. [select] c. gen., succumb to, τῆς ὥρας, τοῦ κάλλους, Ael.VH12.52, Ps.-Luc. Charid.9; “κόρης” Philostr.Her.8.2, prob. in Eun.Hist.p.238D.
5. [select] to be established by argument, proved, Phld.Sign.29,33.
II. [select] c. part., to be caught or detected doing a thing, “οὔτε σὺ ἁλώσεαι ἀδικέων” Hdt.1.112; ἐπιβουλεύων ἐμοὶ . . ἑάλωκε ib.209; “ἐὰν ἁλῷς ἔτι τοῦτο πράττων” Pl.Ap.29c; with Subst. or Adj., “οὐ γὰρ δὴ φονεὺς ἁλώσομαι” S.OT576; “μοιχὸς γὰρ ἢν τύχῃς ἁλούς” Ar.Nu.1079; “ἁ. ἐν κακοῖσι” S. Ant.496.
2. [select] freq. as law-term, to be convicted and condemned, “λιποταξίου γραφὴν ἡλωκέναι” D.21.105, cf. Antipho 2.2.9, 2.3.6; ἁ. “μιᾷ ψήφῳ” And.4.9:—c. gen. criminis, <*>῾λῶναι ψευδομαρτυριῶν, ἀστρατείας, ἀσεβείας, etc. (sc. γραφήν), v. sub vocc.; ἁ. θανάτου to be convicted of a capital crime, Plu.2.552d; ἁλοῦσα δίκη conviction, Pl.Lg. 937d; of false evidence, ὁπόσων ἂν μαρτυρίαι ἁλῶσιν ibid.
So Celsus's statement comes after an Emperor embraced their doctrines and was defeated, conquered, overcome etc. Otherwise the whole thing doesn't make any sense. Compare that with what immediately preceded this statement:
all were to do the same as you, you surely do not say that if the Romans were, in compliance with your wish, to neglect their customary duties to gods and men, and were to worship the Most High, or whatever you please to call him, that he will come down and fight for them, so that they shall need no other help than his. For this same God, as yourselves say, promised of old this and much more to those who served him, and see in what way he has helped them and you! They, in place of being masters of the whole world, are left with not so much as a patch of ground or a home; and as for you, if any of you transgresses even in secret, he is sought out and punished with death
The idea seems to be that the defeat of this Emperor is like the defeat of the Jews during the bar Kochba revolt. In other words, the Christian god has had a series of defeats for its leaders which proves the superiority of the Roman gods.