God is spirit, not body
If Celsus understood what we say about the Spirit of God, and that “as many as are led by the Spirit of God, these are sons of God” (Romans 8:14), he would not have declared on his own, as though it came from us, that God put his own spirit into a body and sent it down here. For God always gives a share of his own Spirit to those who are able to partake of him; yet the Spirit does not come to be in the worthy by being cut off and divided. For the Spirit we speak of is not a body, just as fire is not a body either, which God is said to be in the words: “Our God is a consuming fire” (Hebrews 12:29; Deuteronomy 4:24). All these things are said figuratively, to present the nature of what is grasped by the mind by means of familiar and bodily names.
Just as, if sins are said to be wood and hay and straw, we shall not say that sins are bodies, and if good deeds are said to be gold and silver and precious stone (1 Corinthians 3:12), we shall not say that good deeds are bodies; so too, even if God is said to be a “fire consuming” the “wood” and the “hay” and the “straw” and every substance of sin, we shall not think of him as a body. And just as, when he is called “fire,” we do not think of him as a body, so when God is called “spirit,” we do not say that he is a body.
For Scripture is accustomed to call the things grasped by the mind “spirits” and “spiritual,” to set them apart from things perceived by the senses. For example, when Paul says: “But our sufficiency is from God, who also made us sufficient as ministers of a new covenant, not of the letter but of the spirit; for the letter kills, but the spirit gives life” (2 Corinthians 3:5–6), by “letter” he meant the sense-bound interpretation of the divine writings, and by “spirit” the interpretation grasped by the mind.
So it is, then, with “God is spirit” (John 4:24). Since both Samaritans and Jews were carrying out the commands of the law in a bodily way and in figures, the Saviour said to the Samaritan woman: “The hour is coming when neither in Jerusalem nor on this mountain will they worship the Father” (John 4:21); “God is spirit, and those who worship him must worship in spirit and truth” (John 4:24). By these words he taught that God must be worshipped not in the flesh and with fleshly sacrifices, but “in spirit.” Indeed, he himself may be thought of as “spirit” in keeping with the way one serves him “in spirit” and with the mind.
Moreover, the Father must be worshipped not in figures but “in truth,” which “came through Jesus Christ” after the law was given “through Moses” (John 1:17). For “when we turn to the Lord” (“now the Lord is the Spirit”), “the veil” that lies on the heart “whenever Moses is read” “is taken away” (2 Corinthians 3:15–17).
Greek
Εἰ δὲ συνίει Κέλσος ἃ λέγομεν περὶ πνεύματος θεοῦ, καὶ ὅτι „ὅσοι πνεύματι θεοῦ ἄγονται, οὗτοι υἱοὶ θεοῦ εἰσιν,“ οὐκ ἂν ἑαυτῷ ὡς ἀφ᾿ ἡμῶν ἀπεφήνατο ὅτι πνεῦμα ἴδιον ἐμβαλὼν εἰς σῶμα ὁ θεὸς δεῦρο κατέπεμψεν. ἀεὶ γὰρ ὁ θεὸς μεταδίδωσι τοῖς δυναμένοις μετέχειν αὐτοῦ τοῦ ἰδίου πνεύματος, οὐ κατ᾿ ἀποτομὴν καὶ διαίρεσιν ἐγγινομένου τοῖς ἀξίοις. οὐδὲ γὰρ σῶμα τὸ καθ᾿ ἡμᾶς πνεῦμα, ὡς οὐδὲ σῶμα τὸ πῦρ, ὅπερ εἶναι λέγεται θεὸς ἐν τῷ· „ὁ θεὸς ἡμῶν πῦρ καταναλίσκον.“ πάντα γὰρ ταῦτα τροπικῶς λέγεται εἰς παράστασιν τὴν ἀπὸ τῶν συνήθων καὶ σωματικῶν ὀνομάτων τῆς νοητῆς φύσεως. καὶ ὥσπερ, ἐὰν λέγηται τὰ ἁμαρτήματα ξύλα εἶναι καὶ χόρτος καὶ καλάμη, οὐκ ἐροῦμεν εἶναι τὰ ἁμαρτήματα σώματα, καὶ ἐὰν λέγηται τὰ ἀνδραγαθήματα χρυσὸς εἶναι καὶ ἄργυρος καὶ λίθος τίμιος, οὐ φήσομεν εἶναι τὰ ἀνδραγαθήματα σώματα· οὕτω κἂν λέγηται ὁ θεὸς εἶναι „πῦρ καταναλίσκον“ τὰ „ξύλα“ καὶ τὸν „χόρτον“ καὶ τὴν „καλάμην“ καὶ πᾶσαν οὐσίαν ἁμαρτίας, οὐ σῶμα αὐτὸν νοήσομεν. ὡς δ᾿ ἐὰν λέγηται „πῦρ,“ οὐ σῶμα νοοῦμεν αὐτὸν, οὕτως ἐὰν λέγηται „πνεῦμα“ ὁ θεὸς, οὐ σῶμα αὐτὸν λέγομεν εἶναι. πρὸς γὰρ ἀντιδιαστολὴν τῶν αἰσθητῶν ἔθος τῇ γραφῇ τὰ νοητὰ ὀνομάζειν πνεύματα καὶ πνευματικά· οἷον ἐὰν λέγῃ ὁ Παῦλος· „ἀλλ᾿ ἡ ἱκανότης ἡμῶν ἐκ τοῦ θεοῦ, ὃς καὶ ἱκάνωσεν ἡμᾶς διακόνους καινῆς διαθήκης, οὐ γράμματος ἀλλὰ πνεύματος· τὸ γὰρ γράμμα ἀποκτέννει, τὸ δὲ πνεῦμα ζῳο ποιεῖ,“ „γράμμα“ μὲν τὴν αἰσθητὴν ὠνόμασεν ἐκδοχὴν τῶν θείων γραμμάτων „πνεῦμα“ δὲ τὴν νοητήν. οὕτω τοίνυν καὶ ἐν τῷ „πνεῦμα ὁ θεός“· ἐπεὶ καὶ Σαμαρεῖς καὶ Ἰουδαῖοι σωματικῶς καὶ τυπικῶς ἐποίουν τὰ προσταττόμενα ὑπὸ τοῦ νόμου, εἶπεν ὁ σωτὴρ πρὸς τὴν Σαμαρεῖτιν· „ὅτι ἔρχεται ὥρα, ὅτε οὔτε ἐν Ἱεροσολύμοις οὔτε ἐν τῷ ὄρει τούτῳ προσκυνήσουσι τῷ πατρί· πνεῦμα ὁ θεὸς, καὶ τοὺς προσκυνοῦντας αὐτὸν ἐν πνεύματι καὶ ἀληθείᾳ δεῖ προσκυνεῖν.“ δι᾿ ὧν ἐδίδαξεν ὅτι οὐκ ἐν σαρκὶ „δεῖ προσκυνεῖν“ καὶ σαρκίναις θυσίαις τὸν θεὸν ἀλλ᾿ „ἐν πνεύματι.“ καὶ γὰρ αὐτὸς ἀνάλογον (τῷ) „ἐν πνεύματι“ καὶ νοητῶς λατρεύειν τινὰ αὐτῷ „πνεῦμα“ νοηθείη ἄν. ἀλλὰ καὶ οὐκ ἐν τύποις „προσκυνεῖν δεῖ“ τῷ πατρὶ ἀλλ᾿ „ἐν ἀληθείᾳ,“ ἥτις „διὰ Ἰησοῦ Χριστοῦ ἐγένετο“ μετὰ το δοθῆναι τὸν νόμον „διὰ Μωϋσέως.“ „ἡνίκα“ γὰρ „ἐὰν ἐπιστρέψωμεν πρὸς κύριον“ („ὁ δὲ κύριος τὸ πνεῦμά ἐστι“), „περιαιρεῖται τὸ“ τῇ καρδίᾳ „κάλυμμα“ ἐπικείμενον, „ἡνίκα ἂν ἀναγινώσκηται Μωϋσῆς.“