I see 5 noteworthy possibilities to explain the change between singular and plural, any one of which could be true (and they probably aren't entirely mutually exclusive either):
- Paul unintentionally goes from plural to singular and back again
- When Paul speaks in the singular he has in mind a specific woman in Ephesus
- Paul is teaching against the worship of Diana, which was common in Ephesus
- Paul is talking about families. She = a mother, they = her whole family
- Paul is referring to Eve and making a profound theological statement
Let’s consider each in turn:
1. Paul unintentionally goes from plural to singular and back again
Unintentional shifts like this are not uncommon in spoken or written language (e.g. the word “they” is misused is English all the time). Of course, since Paul was likely using a scribe (see discussion of amanuenses on this site here and here), one cannot help but wonder whether a professional writer would make this mistake.
2. When Paul speaks in the singular he has in mind a specific woman in Ephesus
Timothy was leading the church in Ephesus (1 Timothy 1:3), a major city in its region, where Paul himself had lived for more than 2 years (see Acts 19). This means Paul had quite a bit of personal knowledge regarding the people in Ephesus and the problems they faced. He’s able to be much more specific than he could be in writing to say, the Romans. When he wrote to them he had never been to Rome.
It would be of great benefit to know what questions Timothy may have asked that prompted the letter, but it is possible that, given Paul’s knowledge of the people, congregation(s), and culture, Paul is offering advice to Timothy regarding specific individuals when he speaks in the singular.
This has also been suggested as a possibility in understanding verses 11-12, which also use “woman”, whereas the previous verses referred to “women”. In this case, singular is advice with respect to an individual, and plural is advice for people in general.
3. Paul is teaching against the worship of Diana, which was common in Ephesus
Ephesus was home to the temple of Diana and was a hotspot for the worship of Diana (see Acts 19:23-28). In some expressions of the lore, believers in Diana saw her as the goddess of pregnancy, and would seek her protection during childbirth (see here).
The cult of Diana interpretation is interesting because Paul was just cautioning against hairstyles they were known for in verse 9 (see Stott's work here p. 84).
In this case, Paul is telling Timothy, when a woman comes to you with concern about childbirth and is considering Diana worship, here is the counsel to give her: she will be saved by the true and living God, and His blessings will be poured out if she and her husband are faithful.
Note that “saved” here could mean physical protection or it could have in mind an eternal blessing, or both. In other words, whether the blessings come in this life or in eternity, they will come from the true and living God, not from Diana.
(Additional context re the cult of Diana can be found in the aforementioned work by Stott, with summaries in my thoughts on a related question here, and an article by Gregory Brown here)
4. Paul is talking about families. She = a mother, they = her whole family
If Paul has in mind the eternal well-being of a whole family the last clause of verse 15 expresses the behavior he hopes will be exhibited by all in the family. But only the mother in the family is bearing children, so “she” is the appropriate term in the first clause.
This potentially carries interesting implications about salvation—that spiritual progression and eternal opportunities are a family affair.
5. Paul is referring to Eve and making a profound theological statement
Verses 13 & 14 are about Adam and Eve. If they are the antecedents for verse 15, “she” is a reference to Eve and “they” means Adam & Eve. Then Paul might be saying something like this:
Redemption from the Fall will come because Eve will safely carry into the world descendants, from whom will come her Savior. Christ is of the seed of Eve, and so her Salvation is indeed a result of her motherhood (see Genesis 3:15 as well as Dottard’s post here). Her role as a mother is a critical part of God’s plan to offer salvation to her and to the entire human family.
What about the “they”? Adam isn’t off the hook here. Eve does the child-bearing, but both mother and father have a sacred duty—together—to bring up their family in “faith and love and holiness, with self-control.” The righteous branch of their posterity, from which Christ will come, is borne by Eve, but is to be raised & taught by both Adam and Eve.
I don’t know which of these Paul meant—but the 5th option intrigues me the most. In this case, Paul is teaching about Adam, Eve, and family, and using them as examples to be considered and emulated by their descendants.
My own thoughts on what the broader New Testament teaches on this subject--and the vital role of women of faith--can be found here