John 1:7: οὗτος ἦλθεν εἰς μαρτυρίαν, ἵνα μαρτυρήσῃ περὶ τοῦ φωτός, ἵνα πάντες πιστεύσωσιν δι' αὐτοῦ.
Everytime I have read this, without really thinking about it, I assumed that the αὐτοῦ refers to the light=Jesus.
"...so that everyone might believe through it/him (i.e. the light, that is Jesus.")
But I note that Nonnus' paraphrase has
Nonnus 1:7b: ἵνα πάντες ἑνὸς κήρυκος ἰωῇ ὀρθὴν πίστιν ἔχοιεν...
...so that all might through the voice of one ...

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