My dear friend, please don’t confuse the issue with the genitive—that’s not the point; the translation and context is, however. So, I have gone over some of what I have written you and hopefully improve the clarity.
As I said, there are 8 occurrences of the word μιᾶς in the New Testament. Here they are with their meanings (pay particular attention to the context of each):
Luke 14:18 καὶ ἤρξαντο ἀπὸ μιᾶς πάντες παραιτεῖσθαι. ὁ πρῶτος εἶπεν αὐτῷ• ἀγρὸν ἠγόρασα καὶ ἔχω ἀνάγκην ἐξελθὼν ἰδεῖν αὐτόν• ἐρωτῶ σε, ἔχε με παρῃτημένον.
They all as one began to make excuses. "The first said to him, 'I have bought a field, and I must go and see it. Please have me excused.'
Adjective: Genitive Singular Feminine
"Note: “I have bought one field, only—not two or three, only one …”
Luke 17:34 λέγω ὑμῖν, ταύτῃ τῇ νυκτὶ ἔσονται δύο ἐπὶ κλίνης μιᾶς, ὁ εἷς παραλημφθήσεται καὶ ὁ ἕτερος ἀφεθήσεται•
I tell you, in that night there will be two people in one bed. The one will be taken, and the other will be left.
Adjective: Genitive Singular Feminine
"Note: “two in one bed, one taken, one left”
Luke 22:59 καὶ διαστάσης ὡσεὶ ὥρας μιᾶς ἄλλος τις διϊσχυρίζετο λέγων• ἐπ' ἀληθείας καὶ οὗτος μετ' αὐτοῦ ἦν, καὶ γὰρ Γαλιλαῖός ἐστιν.
After about one hour passed, another confidently affirmed, saying, "Truly this man also was with him, for he is a Galilean!"
Adjective: Genitive Singular Feminine
"Note: “About an hour …”
Acts 24:21 ἢ περὶ μιᾶς ταύτης φωνῆς ἧς ἐκέκραξα ἐν αὐτοῖς ἑστὼς ὅτι περὶ ἀναστάσεως νεκρῶν ἐγὼ κρίνομαι σήμερον ἐφ' ὑμῶν.
“[U]nless it is for this one thing that I cried standing among them, 'Concerning the resurrection of the dead I am being judged before you today!'"
Adjective: Genitive Singular Feminine
"Note: “I am being judged for one thing only — not two or three, only one!”
Hebrews 12:16 μή τις πόρνος ἢ βέβηλος ὡς Ἠσαῦ, ὃς ἀντὶ βρώσεως μιᾶς ἀπέδετο τὰ πρωτοτόκια ἑαυτοῦ.
[Le]st there be any sexually immoral person, or profane person, like
Esau, who sold his birthright for one meal.
Adjective: Genitive Singular Feminine
"Note: “One meal” not two
1 Timothy 3:2 δεῖ οὖν τὸν ἐπίσκοπον ἀνεπίλημπτον εἶναι, μιᾶς γυναικὸς ἄνδρα, νηφάλιον σώφρονα κόσμιον φιλόξενον διδακτικόν,
The overseer therefore must be without reproach, the husband of one wife, temperate, sensible, modest, hospitable, good at teaching;
Adjective: Genitive Singular Feminine
"Note: “Same word, why the exception?”
Titus 1:6 εἴ τίς ἐστιν ἀνέγκλητος, μιᾶς γυναικὸς ἀνήρ, τέκνα ἔχων πιστά, μὴ ἐν κατηγορίᾳ ἀσωτίας ἢ ἀνυπότακτα.
if anyone is blameless, the husband of one wife, having children who believe, who are not accused of loose or unruly behavior.
Adjective: Genitive Singular Feminine
"Note: “Same word, why the exception?”
Let's look at some other examples:
"But because of immoralities, each man is to have his own wife, and each woman is to have her own husband. The husband must fulfill his duty to his wife, and likewise also the wife to her husband." - 1 Corinthians 7:2-3 NASB (Contextually, a plurality is not suggested here.)
1 Corinthians chapter 7 discusses marriage and it is always in the context of "wife" (singular) and "husband" (singular). It does not make sense for the singular words to be used, if it is possible to have more than one wife. If it were acceptable to God to have more than one wife, then the word "wives" would have to have been used here. The wording of 1 Corinthians chapter 7 completely excludes the possibility of polygamy, in my opinion—unless, one applies a strange new hermeneutics.
Ephesians chapter 5 (verses 22-33) discuss marriage. Here again we do see the plural "wives" used. However, it is used because Paul is writing to the overall category of husbands and wives.
"Wives be subject to your own husbands, as to the Lord." - Ephesians 5:22 NASB
"Husbands, love your wives, just as Christ also loved the church and gave Himself up for her," - Ephesians 5:25 NASB
Notice that in verse 23 his message becomes more personal:
"For the husband is the head of the wife, as Christ also is the head of the church, He Himself being the Savior of the body." - Ephesians 5:23 NASB
Then I pointed out:
"Let us rejoice and be glad and give the glory to Him, for the marriage of the Lamb has come and His bride [the church] has made herself [not themselves] ready." - Revelation 19:7 NASB
Friend, since none of these indicates a plurality—unless you choose use an Old Testament polygamous paradigm as your hermeneutical tool. I choose to accept the contextual and New Testament linguistical approach.
Again, since in my opinion, the overwhelming use of the Greek points in the solid direction of monogamy and since we can easily deduct this from the context of the other examples, why should we make the only other exception that of relating to wives? It just does not make sense to me. Friend, in times past, God winked at such practices (my words here, not Jesus’ because I know that he was addressing the issue of divorce here) but he now calls all men to repentance.
May God bless you,
Jim
P.S. And as far as I can determine, the use of the μία form is just as singular, no matter how you slice it as it regards marriage.