Death either ends all life or leaves the soul alone, and in neither case can judgment be just
Athenagoras is arguing that if death is either total extinction or the survival of the soul alone, God's judgment of human deeds cannot be just.
For either death is the complete extinction of life, the soul being dissolved together with the body and destroyed along with it, or the soul remains by itself indissoluble, unscattered, and incorruptible, while the body is destroyed and dissolved, no longer preserving any memory of what was done or any awareness of what it suffered. If human life is completely extinguished, then clearly no care will be shown for human beings who no longer live, and there will be no judgment for those who lived in virtue or in wickedness. Instead, the practices of lawless life will roll in again, along with the swarm of absurdities that follow them, and the chief point of this lawlessness: godlessness. But if the body is destroyed and each of its dissolved parts goes to what is akin to it, while the soul remains by itself as incorruptible, even so there will be no place for judgment against it, since justice would not be present. For it is not lawful to suppose that any judgment comes from God and by God unless what is just belongs to it. And what is just does not belong to the judgment unless the one who performed the justice or the lawlessness is preserved. For the one who performed each of the deeds in life on which judgment is passed was a human being, not a soul by itself. To speak in summary, this argument will preserve justice in no case.
Greek
Ἤτοι γὰρ παντελής ἐστι σβέσις τῆς ζωῆς ὁ θάνατος, συνδιαλυομένης τῷ σώματι τῆς ψυχῆς καὶ συνδιαφθειρομένης, ἢ μένει μὲν καθ᾿ ἑαυτὴν ἄλυτος ἡ ψυχή, ἀσκέδαστος, ἀδιάφθορος, φθείρεται δὲ καὶ διαλύεται τὸ σῶμα, οὐδεμίαν ἔτι σῶζον οὔτε μνήμην τῶν εἰργασμένων οὔτ᾿ αἴσθησιν τῶν ἐπ᾿ αὐτῇ παθημάτων. Σβεννυμένης μὲν γὰρ παντελῶς τῆς τῶν ἀνθρώπων ζωῆς, οὐδεμία φανήσεται τῶν ἀνθρώπων οὐ ζώντων φροντίς, οὐ τῶν κατ᾿ ἀρετὴν ἢ κακίαν βεβιωκότων ἡ κρίσις, ἐπεισκυκληθήσεται δὲ πάλιν τὰ τῆς ἀνόμου ζωῆς καὶ τῶν ταύτῃ συνεπομένων ἀτόπων τὸ σμῆνος, τό τε τῆς ἀνομίας ταύτης κεφάλαιον ἀθεότητος. Εἰ δὲ φθείροιτο μὲν τὸ σῶμα καὶ χωροίη πρὸς τὸ συγγενὲς τῶν λελυμένων ἕκαστον, μένοι δὲ ἡ ψυχὴ καθ᾿ ἑαυτὴν ὡς ἄφθαρτος, οὐδ᾿ οὕτως ἕξει χώραν ἡ κατ᾿ αὐτῆς κρίσις, μὴ προσούσης δικαιοσύνης· ἐπειδὴ μηδὲ θεμιτὸν ὑπολαμβάνειν ἐκ θεοῦ καὶ παρὰ θεοῦ γίνεσθαί τινα κρίσιν, ᾗ μὴ πρόσεστι τὸ δίκαιον. Οὐ πρόσεστι δὲ τῇ κρίσει τὸ δίκαιον, μὴ σωζομένου τοῦ διαπραξαμένου τὴν δικαιοσύνην ἢ τὴν ἀνομίαν· ὁ γὰρ διαπραξάμενος ἕκαστον τῶν κατὰ τὸν βίον ἐφ᾿ οἷς ἡ κρίσις ἄνθρωπος ἦν, οὐ ψυχὴ καθ᾿ ἑαυτήν. Τὸ δὲ σύμπαν εἰπεῖν, ὁ λόγος οὗτος ἐπ᾿ οὐδενὸς φυλάξει τὸ δίκαιον.