"Firstborn" In Luke 2:7 And The Alleged Perpetual Virginity Of Mary

From Gregory Lanier's new commentary on Luke:

"Also, because prōtotokos here [in Luke 2:7] is modified by 'her,' it registers at the human level and does not convey the transcendence of Rom 8: 29; Col 1: 15; and Heb 1: 6." (Christian Standard Commentary: Luke [B&H Publishing Group, 2025], approximate Kindle location 4693)

Luke uses "only begotten" elsewhere (7:12, 9:38). He could have used it in 2:7, which would have implied the prerogatives, honors, and such of the "firstborn" terminology without casting doubt on Mary's perpetual virginity. In a culture in which women normally have multiple children, like ancient Israel, a woman whose child is called "firstborn" is normally expected to go on to have others or thought to have had others already, and Luke's gospel refers to others if the gospel is interpreted in its most natural sense (8:19). To refer to a woman's child as "firstborn" when she may not have any other children, but is expected to have more, is different than referring to the child as "firstborn" when writing after you know there were no other children. You could do the latter, but it would be less natural. Even if a term takes on additional uses over time, you should ask what the best explanation is of how the term originated. That has implications for later usage. "Firstborn" makes the most sense as a term originating in a context involving multiple children. That likely was the original meaning and the usual meaning afterward, even though exceptions developed under some circumstances. The issue here is how we best explain the terminology, not how it might be interpreted.