John the witness: ἐγένετο, ἀπεσταλμένος, εἰς μαρτυρίαν, and ἀλλʼ ἵνα

Says Ἐγένετο ἄνθρωπος (egeneto anthrōpos, "there came a man") introduces John with ἐγένετο. This is the verb used for created things (1:3), not the ἦν used for the Word (1:1–2). ἀπεσταλμένος (apestalmenos) is the perfect passive participle of ἀποστέλλω ("send"). With παρὰ θεοῦ, it marks John as commissioned by God; the perfect presents him as one who stands sent. ὄνομα αὐτῷ Ἰωάννης is a verbless clause with a dative of possession ("his name was John").

Says 1:7 states purpose three times: - εἰς μαρτυρίαν (eis martyrian), "for witness"; - ἵνα μαρτυρήσῃ περὶ τοῦ φωτός, "to testify about the light," which spells out the first; - ἵνα πάντες πιστεύσωσιν διʼ αὐτοῦ, "so that all might believe through him," which is the further goal.

διʼ αὐτοῦ most naturally refers to John as the means of the testimony. Believers trust in the light, not in John.

Says In 1:8, οὐκ ἦν ἐκεῖνος τὸ φῶς has an emphatic ἐκεῖνος and an articular predicate: John was not the light. ἀλλʼ ἵνα μαρτυρήσῃ is elliptical, and a verb such as "he came" (from 1:7) must be supplied. Compare the similar ἀλλʼ ἵνα in 9:3; 13:18; 15:25.

Implies The prologue honors John and limits his role. He is a sent witness, not the light. Jesus later calls him ὁ λύχνος, "the lamp" (5:35).

Uncertain Whether the ellipsis is better filled with "he came" or read as an independent purpose clause. The sense is the same either way.