God is known by the mind and seen by a pure heart
Supposing that we hold the doctrine of the resurrection for the sake of knowing and seeing God, Celsus strings together whatever he likes, and says something like this: “When they are shut out on every side and refuted, they come back again, as if they had heard nothing, to the same question: ‘How then are we to know and see God? And how are we to go to him?’”
Let anyone who wishes know, then, that even if for other purposes we need a body, because we are in a bodily place, and a body suited to the nature of that bodily place, and even if, since we need the body, we put on over the tent what we have described, yet for the knowledge of God we have no need of a body at all. For what knows God is not the eye of the body but the mind, which sees what is “in the image” (Genesis 1:26–27) of the Creator, and which by the providence of God has received the power to know God.
And what sees God is a pure heart, from which there no longer “come forth evil thoughts,” no “murders,” no “adulteries,” no “fornications,” no “thefts,” no “false witness,” no “blasphemies” (Matthew 15:19), no “evil eye” (Mark 7:22), nor anything else that is wrong. That is why it is said: “Blessed are the pure in heart, for they shall see God” (Matthew 5:8). But since our own free choice is not enough for us to have a heart wholly “pure,” and we need God to create it so, the one who prays with understanding says: “Create in me a pure heart, O God” (Psalm 51:10).
Greek
Οἰόμενος δ᾿ ἡμᾶς διὰ τὸ γνῶναι καὶ ἰδεῖν τὸν θεὸν πρεσβεύειν τὰ περὶ τῆς ἀναστάσεως συνείρει ἑαυτῷ ἃ βούλεται καὶ τοιαῦτά φησιν· ὅταν δὴ πάντοθεν ἐξείργωνται καὶ διελέγχωνται, πάλιν ὥσπερ οὐδὲν ἀκηκοότες ἐπανίασιν ἐπὶ τὸ αὐτὸ ἐρώτημα· πῶς οὖν γνῶμεν καὶ ἴδωμεν τὸν θεόν; καὶ πῶς ἴωμεν πρὸς αὐτόν; ἴστω οὖν ὁ βουλόμενος ὅτι, κἂν εἰς ἄλλα δεώμεθα σώματος τῷ ἐν τόπῳ σωματικῷ τυγχάνειν, καὶ τοιούτου, ὁποία ἐστὶν ἡ φύσις τοῦ σωματικοῦ τόπου, καὶ δεόμενοι τοῦ σώματος ἐπενδυώμεθα τῷ σκήνει τὰ προειρημένα, ἀλλ᾿ εἰς γνῶσίν γε θεοῦ σώματος οὐδαμῶς χρῄζομεν. τὸ γὰρ γινῶσκον θεὸν οὐκ ὀφθαλμός ἐστι σώματος ἀλλὰ νοῦς, ὁρῶν τὸ „κατ᾿ εἰκόνα“ τοῦ κτίσαντος καὶ τὸ δυνάμενον γινώσκειν θεὸν προνοίᾳ θεοῦ ἀνειληφώς. καὶ τὸ ὁρῶν δὲ θεὸν καθαρά ἐστι καρδία, ἀφ᾿ ἧς οὐκέτι „ἐξέρχονται διαλογισμοὶ πονηροὶ,“ οὐ „φόνοι,“ οὐ „μοιχεῖαι,“ οὐ „πορνεῖαι,“ οὐ „κλοπαὶ,“ οὐ „ψευδομαρτυρίαι,“ οὐ „βλασφημίαι,“ οὐκ „ὀφθαλμὸς πονηρὸς“ οὐδ᾿ ἄλλο τι τῶν ἀτόπων· δι᾿ ἃ λέγεται· „μακάριοι οἱ καθαροὶ τῇ καρδίᾳ, ὅτι αὐτοὶ τὸν θεὸν ὄψονται.“ ἐπεὶ δ᾿ οὐκ αὐτάρκης ἡ ἡμετέρα προαίρεσις πρὸς τὸ πάντῃ „καθαρὰν“ ἔχειν τὴν „καρδίαν,“ ἀλλὰ θεοῦ ἡμῖν δεῖ, κτίζοντος αὐτὴν τοιαύτην, διὰ τοῦτο λέγεται ὑπὸ τοῦ ἐπιστημόνως εὐχομένου· „καρδίαν καθαρὰν κτίσον ἐν ἐμοὶ ὁ θεός.“