Please allow me to backtrack and recant the line of argument I have taken from here in this thread. It is clear to me that I made a scribal error and inverted two clauses, putting them in the wrong order and then proceeded to build a case based on the unbiblical inverted sentence. My bad. I took a shortcut of not including the Greek text and accidentally wandered off into the weeds.
Please allow me to go back to this post here and correct my error.
Jhn 10:24
ἐκύκλωσαν (Surrounded, aorist active indicative) οὖν (therefore) αὐτὸν (to him) οἱ Ἰουδαῖοι (the Jews) καὶ (and) ἔλεγον (said, aorist active indicative) αὐτῷ (to him) Ἕως πότε (how long) τὴν ψυχὴν (the breath) ἡμῶν (of us) αἴρεις (you are taking away, present active indicative)? εἰ (if) σὺ (you) εἶ (are) ὁ Χριστός (the Christ) εἰπὲ (tell, aorist active imperative) ἡμῖν (us) παρρησίᾳ (lit. in an all utterance, i.e. not holding anything back).
So, the Jews surrounded Him and said to Him, "How long are you keeping us in suspense? if you are the Christ tell us in no uncertain terms.
Jhn 10:25
ἀπεκρίθη (answering, aorist active participle) αὐτοῖς (to them) ὁ Ἰησοῦς (the Jesus) Εἶπον (I told, aorist active indicative) ὑμῖν (you) καὶ (and) οὐ (you) πιστεύετε (do not believe, present active indicative)· τὰ ἔργα (the works) ἃ (which) ἐγὼ (I, emphatic) ποιῶ (am doing, present active indicative) ἐν τῷ ὀνόματι (in the name) τοῦ πατρός (of the Father) μου (of me) ταῦτα (these) μαρτυρεῖ (are testifying, present active indicative) περὶ ἐμοῦ (upon of me).
Jesus in response said to them, " I told you and you do not believe. The works that I am doing in my Father's name, these are testifying on my behalf.
Jhn 10:26
ἀλλ᾽ (But) ὑμεῖς (you pl.) οὐ (not) πιστεύετε (are believing, present active indicative) οὐ (not) γὰρ (for) ἐστὲ (you are) ἐκ τῶν προβάτων (out of the sheep) τῶν ἐμῶν (the of me
sheep) καθὼς (just as) εἶπον (I told, aorist active indicative) ὑμῖν (you).
But you are not believing, because you are not out of my sheep. (i.e members of my flock).
Jhn 10:27
τὰ πρόβατα (The sheep) τὰ ἐμὰ (the of me
sheep) τῆς φωνῆς (the voice) μου (of me) ἀκούει, (are listening to) κἀγὼ (and I) γινώσκω (am knowing experientially, present active indicative) αὐτά (them) καὶ (and) ἀκολουθοῦσίν (they are following, present active indicative) μοι (me)
My sheep are listening to My voice and I have a meaningful relationship with them and they are following Me.
You question was, "Perhaps someone here who does know NT Greek can tell us whether the Greek of John 10:26 could possibly mean "You are not of my sheep. [I deduce this] because you do not believe in Me."
So, no. It can't mean that. I inadvertently inverted the clauses and went off on a false tangent.
Let's look at what John 10:26 does actually say.
But you are not believing, because you are not out of my sheep (i.e you are not members of my flock).
Does this mean that
1. only those who are already Jesus' sheep can start to believe in Him? Or does it allow for the idea that
2. those who start to believe in Him become His sheep, and one cannot become one of His sheep without believing in Him and one cannot remain as one of His sheep without continuing to believe in Him? Which is why Jesus knows they are not yet His sheep, because they are not yet believing in Him.
If Jesus had meant to communicate the first option, He would have used the aorist form of the verb
believe and said,
"But
you did not believe (ἐπιστεύσατε, episteusate, as in Matt. 21:32) because
you are not one of my sheep."
But He uses the present tense (πιστεύετε, pisteuete), But
you are not believing, because you
are not out of my sheep.
The evidence that one has become one of Jesus' sheep is that they are now believing in Him. If someone is not presently believing in Him, it is evident that they are not presently His sheep. However, should they start to believe in Him, they will become His sheep. And if they continue to believ in Him, they will continue to be His sheep. This is what the Greek of John 10:26 means.