I have recently read a few articles, in conjunction with a large portion of historical readings, discussing how women in European societies underwent persecution and oppression due to the spread of Christianity. For example, one article discussed how women were the primary beer brewers until it was outlawed due to the reformation. Some even attribute how, prior to the reformation which made brewing by women outlawed, women wore clothing we commonly associate with that of witches because when in the marketplace selling beer they wore tall pointed hats so they could be seen and stood next to cauldrons full of beer to sell in the marketplace. Even the association of cats with witches may have stemmed from female brewers preferring cats to kill the mice trying to eat the stored grain. I don't want to make a blanket statement, but it appears that when we look at older pagan or pre-Christian societies, we see that women had much freedom and were treated better. They were even seen and held in such regard as to be goddesses, warriors, as well as homemakers and brewers, etc... They were held in very high regard.
Why does it seem that women became a target under the spread of Christianity? I understand that the Christian religion has strong views on gender roles, but why the oppression and attack? Did the church or Christianity view women as a threat for some reason? It appears there was such an aggressive oppression of women and I'm not sure where it came from.
The short answer is it depends.
The most important thing to realize here is the vast amount of time and space you're talking about here. Gender norms varied enormously across the European continent and the amount of time from the conversion of the bulk of people in many areas to Christianity to the Reformation was over a thousand years. A huge amount happened in that span of time. Having horrible things happen to women over a thousand years after an area converted to Christianity makes it very hard to link the specific things that you're talking about with "the spread of Christianity."
To hit some specific points "but it appears that when we look at older pagan or pre-Christian societies, we see that women had much freedom and were treated better" is not really true at all. Pagan societies were hardly uniform and had a huge range from relatively egalitarian gender relations to extreme patriarchy (Classical Athens, for example, was a horrible place to be a woman). Also pagan societies didn't stay in the same place, for example in some ways the status of women (specifically widowed women) rose during the Roman Republic.
Here's one quote that I think is instructive:
Hilarion to Alis his sister, heartiest greetings, and to my dear Berous and Apollonarion. Know that we are still even now in Alexandria. Do not worry if when all the others return I remain in Alexandria. I beg and beseech of you to take care of the little child, and as soon as we receive wages I will send them to you. If-good luck to you!-you bear offspring, if it is a male, let it live; if it is a female, expose it. You told Aphrodisias, ‘Do not forget me.’ How can I forget you? I beg you therefore not to worry.
The 29th year of Caesar, Pauni 23. (see: https://diotima-doctafemina.org/translations/anthologies/womens-life-in-greece-and-rome-selections/vii-private-life/249-exposure-of-a-female-child/ )
Female infanticide was common enough in the ancient world that the Romans thought that the Egyptians were strange because it was not practiced there. Pre-Christian Europe was not an oasis of gender equality, quite the opposite.
As for "held in such regard as to be goddesses, warriors" there were occasional female war leaders and warriors both before and after the spread of Christianity and it is quite possible to have a deeply patriarchal society in which figures like goddesses or the Virgin Mary are revered.
Now let's get into brewing specifically.
As you say, brewing was a female trade in many areas for a long time. This persisted long after the spread of Christianity. There also were bans on female brewing in several specific cities. This was as a result of guilds throwing their weight around and trying to stifle competition. This applied to many trades aside from brewing and was enacted under a whole slew of different pretexts. See: Ogilvie, Sheilagh (2019) The European Guilds: An Economic Analysis. Princeton: Princeton University Press for more information about guilds forcing women out of various trades.
Again I want to emphasize the spans of time we're talking about. The area that later became England was certainly mostly Christian in the 300's, while the process of driving women out of the bulk of the brewing trade wasn't really cemented until roughly the Tudors. There's a vast span of time in the middle with large numbers of Christian female brewers.
For more information about these female brewers see: Bennett, Judith M (1996). Ale, beer and brewsters in England: women's work in a changing world, 1300-1600. New York; Oxford: Oxford University Press. Bennett is great on the social analysis, but a bit shaky at times when it comes to the technical aspects of the brewing process.
I'd also like to emphasize that while certain cities (at the urging of guilds) did ban women from selling ale there were never any nation-wide, much-less continent wide bans, nor were women banned from brewing ale for their own household. However, you're right that brewing did change from being female dominated to male dominated in a relatively brief span of time specifically in England.
Why did this take place? Well patriarchy by itself can't explain this change since there was plenty of that before, during, and after this change-over. Witch hysteria certainly didn't help but it wasn't the driving force. The big thing was hops.
Originally English ale didn't have hops. Without hops serving as a preservative, ale had a short shelf life and was often brewed fresh (or "mild") for a specific occasion. This was often drunk partially fermented which would've made it sweet, caloric, and less alcoholic. Aged (or "stale") ale existed but it was harder to produce. This older form of ale having (usually) a short shelf life meant that you couldn't store it or transport it easily. This meant that it was produced in relatively small batches for local consumption. Except in areas like London where there was huge demand, brewing was a pretty small scale and marginal business. That's precisely why it was dominated by women.
Later hopped beer came in from the continent and the use of hops was adopted in England. Hops are great preservatives which means that beer could be stored much longer and shipped about as a trade good. This revolutionized the business of brewing. It meant you could brew in much larger batches and sell your beer much farther from home. This turned brewing from a cottage industry into a major commercial operation. And in a patriarchal society men were hardly going to allow women to dominate a major commercial operation. So they didn't.
It wasn't that there was an increase in the oppression of women. It's just that before hops, brewing was pretty marginal economically while after hops that changed and both before and after hops women were largely kept to the economic margins. This is oppression certainly, but it's not really a big change in the intensity of oppression which was bad enough both while women dominated brewing and later when they didn't.
I suspect that the articles you have been reading have been influenced by the Burning Times narrative: https://en.wikipedia.org/wiki/The_Burning_Times This strain of pop history does correctly point out many examples of oppression of women, specifically about how women were so often targeted by witch hysteria but it has several problems:
-It paints a far too rosy picture of the pagan past. Pagan society could be incredibly patriarchal depending on the time and place. Beware of articles cherry picking the best bits of pagan Europe and the worst bits of Christian Europe and trying to draw a consistent set of contrasts when in reality there was so much variability in both pagan and Christian Europe.
-It massively exaggerates how much pagan folklore etc. survived over a thousand years after the conversion to Christianity. This like is often pushed by some Wiccans trying to claim that there's an unbroken chain of pagan practice that just doesn't exist.
-It takes specific local events (such as women being banned from selling ale in a specific city) and implies that they were national or even continent-wide.
-Witch burning hysteria was certainly horrible, but this brand of pop history gives vastly too high figures for the casualties that can't be supported by historical evidence.
For an academic feminist look at female brewers and how men came to dominate that industry in England you can't go wrong with Ale, beer and brewsters in England: women's work in a changing world, 1300-1600.