Who sent Jesus, and why
Jesus also taught us who it was that sent him, in the words “No one has known the Father except the Son” (Matthew 11:27; compare Luke 10:22), and in “No one has ever seen God; and he who is indeed the only-begotten God, who is in the bosom of the Father, he has made him known” (John 1:18). It was he who, speaking of God, declared to his true disciples what concerns God; and since we find traces of this in the Scriptures, we have starting points for speaking about God. In one place we hear, “God is light, and in him there is no darkness at all” (1 John 1:5); in another, “God is spirit, and those who worship him must worship in spirit and truth” (John 4:24).
Moreover, the purposes for which the Father sent him are countless. Let anyone who wishes learn them, partly from the prophets who proclaimed him beforehand, partly from the evangelists; and he will learn not a few things from the apostles as well, and above all from Paul. Further, he gives light to the godly and will punish sinners. Celsus did not see this when he wrote: “and to give light to the godly, and to have mercy on those who sin or who have repented.”
Greek
Ἐδίδαξε δὲ ἡμᾶς ὁ Ἰησοῦς καὶ ὅστις ἦν ὁ πέμψας ἐν τῷ „οὐδεὶς ἔγνω τὸν πατέρα. εἰ μὴ ὁ υἱὸς,“ καὶ τῷ „θεὸν οὐδεὶς ἑώρακε πώποτε· καὶ μονογενής γε ὢν θεὸς. ὁ ὢν εἰς τὸν κόλπον τοῦ πατρὸς, ἐκεῖνος ἐξηγήσατο,“ ἐκεῖνος θεολογῶν ἀπήγγειλε τὰ περὶ θεοῦ τοῖς γνησίοις αὐτοῦ μαθηταῖς· ὧν ἴχνη ἐν τοῖς γεγραμμένοις εὑρίσκοντες ἀφορμὰς ἔχομεν θεολογεῖν. ὅπου μὲν ἀκούοντες· „ὁ θεὸς φῶς ἐστι, καὶ σκοτία οὐκ ἔστιν ἐν αὐτῷ οὐδεμία.“ ὅπου δέ· „πνεῦμα ὁ θεὸς, καὶ τοὺς προσκυνοῦντας αὐτὸν ἐν πνεύματι καὶ ἀληθείᾳ δεῖ προσκυνεῖν.“ ἀλλὰ καὶ ἐφ᾿ οἷς ἔπεμψεν αὐτὸν ὁ πατὴρ μυρία ἐστὶν. ἅτινα ὁ βουλόμενος μανθανέτω, πῇ μὲν ἀπὸ τῶν προκηρυξάντων περὶ αὐτοῦ προφητῶν πῇ δ᾿ ἀπὸ τῶν εὐαγγελιστῶν· οὐκ ὀλίγα δ᾿ εἴσεται καὶ ἀπὸ τῶν ἀποστόλων καὶ μάλιστα Παύλου. ἀλλὰ καὶ τοὺς μὲν εὐσεβοῦντας οὗτος φωταγωγεῖ τοὺς δὲ ἁμαρτάνοντας κολάσει, ὅπερ οὐκ ἰδὼν ὁ Κέλσος πεποίηκε· καὶ τοὺς μἐν εὐσεβοῦντας φωταγωγήσων τοὺς δὲ ἁμαρτάνοντας ἢ μεταγνόντας ἐλεήσων.