Why does the Catholic Church hold Mary's virginity and the absence of brothers against the historians?

Question

Jesus does not have a brother in the catholic tradition, his mother Mary is a perpetual virgin, which can hardly be compatible with having several children.

Yet in his epistle to the Galatians (1, 19), Paul calls James "the brother of the Lord". In the first letter to the Corinthians (9: 4-5), he mentions other brothers of the Lord who have the right to take their wives during their apostolic mission. It is clear in Paul's formulation that compares his rights with "other apostles and the Lord’s brothers, and the apostle Peter" that he does not attribute the qualifier of brother of the Lord only to a few specific individuals. It does not stand as synonym of disciple.

From this, several historians hold the position that either Joseph or Mary had children together or from previous relationships for Joseph like P-A. Bernheim¹ , or F. Blanchetière² , who point out that, Paul never qualifies Peter or John as brother of the Lord, or Fr John P. Meier who denies³ the theory of cousins that never appears in the Greek version of the Old Testament in which the term adelphos marks exclusively the fraternal bond of blood or right.

However the Catholic church and many Catholic exegetes believe that Mary didn't had other children, according to the Catechism of the Catholic Church, following the traditional reading based on the later belief in the perpetual virginity of Mary, following Jerome ⁴, the first Father of the Church to argue against the siblings theory for the benefit of the cousins one at the end of the fourth century. They also recuse the half-brothers and sisters theory presented in an apocryphal gospel from James, around 180, born of a first marriage of Joseph from previous relationships.

Why these "Brothers of the Lord" have been embarrassing for the Catholic Church which make them gradually forgotten and lose their quality of brothers? Why at the same time as the cult of chastity develops, whose mother of Jesus becomes the symbol and which will find its apogee in the doctrine of its perpetual virginity?

_{Note : Other like Assyrian and part of protestants hold this doctrine as well but I narrow my question to the Catholic Church as far as the different schisms had not yet been pronounced when the doctrine was created.}

Answer 1

According to @SLM the earliest belief was Mary/Joseph had children after Christ's birth. Origin says the source of ever-virgin (EV) and step-brother explanation is Infancy Gospel of James [where he presents himself as the half-brother of Jesus. ed O.P.]. Nothing about politics. Jerome couldn't bear the thought of a non-virgin Joseph, so invented the cousin theory. But in all that consideration, there's not a mention that he is aware of in a sibling conflict with Jerusalem or Rome. At least on the ever virgin doctrine.

It is therefore Jerome who would have created this belief to 383 by its significant influence during these three years spent in Rome, including his zeal to advocate asceticism. Even though this belief is already inscribed in the symbol of faith of St. Epiphanius, in 374. The reason he believed and created this belief can maybe be found in Against Helvidius and through is whole life. Indeed Jerome defends throughout his life the possibility for women to have a consecrated life according to Philippe Henne. That would have lead him to defend the virginity of women in this treatise. Indeed Helvidius denied the perpetual virginity of Mary, saying it did not matter, and defended that Jesus had brothers but using different sources than the Gospel of James. Jerome, in the words of the Bible, defended that the concept of brother is broader in the gospels.

This idea would then have spread, while the status of women in Rome at the time of Jerome gave way to a large emancipation for the wealthy women of Rome at the time; the appearance of consecrated women encouraged by Jerome is therefore a novelty that is frowned upon by Roman society. But supported by women of influences and devotees to Rome according to Philippe Henne, like Marcella, friend of Pope Damase, then other women of Rome like Paule to whom he teaches the Bible and exegesis.

The doctrine is then proclaimed as a "truth of Faith" at the Second Council of Constantinople in 553, which pronounces in the second anathema:

"The Word of God, incarnate in the holy and glorious Mother of God and always Virgin Mary, is born of her"

As an attempt to sum-up and conclude, the reason the Catholic Church hold Mary's virginity and the absence of brothers against the historians is due to ideas of Jerome. Okay, that's my interpretation from my historical research. I'm happy it raised controversial attention. Feel free to discuss it or propose another hypothesis ?

As an opening question some points still remains unclear like how the spreading of the doctrine in Jerome's social circles women of devout reached the whole Church. Maybe he has to search in the spreading of the Vulgate that Jerome wrote ? And another is what about the reason given nowadays as historical knowledge have improved? Why didn't this doctrine shifted with the time and scientific knowledge, like it shifted from geocentrism?