Hi, AstroOliver!
It seems as though you have been reading my mind!
I have spent the past 2 months trying to collect as many material on this as possible, both from literature and from astrologers who, on occasions, do not agree with everything that has been in said in it and have their own approach. So far, I don't think that i have been able to find either a classification that every one would agree on or a list that would make much sense to me when everything is taken into account.
Oddly enough, I don't think that good explanations or even lists can be found very often in literature (or maybe my list of references is too short when it comes to mundane astrology) which maybe isn't all that strange given that such lists are usually provided in literature that also contains the lists of countries and nations and their corresponding signs which, as you, of course, know, often become outdated soon after publishing due to constant geopolitical changes.
Having said that, I have to ask you if you are familiar with the origin of this classification? (the book, the author?)
Now, as for the major religions (and the philosophies that accompany them), the more I look at the lists provided by different authors, the more confused I get. I have just spent about 1/2 hour meditating on this list and I'm not sure that I can make a parallel between the astrological signs mentioned in t and what seems like the most apparent manifestation of these religious movements/groups or even the professed philosophy, holly scriptures etc. Whilst some parallels sound familiar all right, other came as a surprise.
Of course, when it comes to religions and religious movements, we are usually restricted to the symbolics of signs and their correlation with the philosophy/religion in its essence because, in most (if not all) of the cases, we lack that most important information on which the astrological readings are usually based and that is- the time of birth. The facts are mixed with myths, the calendars have changed, the facts have been politicised and so on . Also, even if the date and time of the prophet's birth were known, many would still disagree with the idea of using that time as the time of birth of the religion professed by these people and would say that the moment when the first "public gathering" took place should be taken as the only relevant time (event chart, basically) which, again, is something we are not familiar with in most of the cases.
So, we're left with the symbolics. Or, with the era (i.e., ex.Age of Pisces). But, at this point, i find it so very unconvincing that a period f time as long as a whole age can determine the quality of such a massive and important movement that has influenced (and that still influences) the development of the human society (in both positive and negative way) on many planes.Here I may be completely wrong and under the influence of my Mercurian nature that feels that such descriptions are not precise enbough.
On the one hand- Christianity was born during the Age of Pisces and is commonly accepted as a "Piscean religion" but, on the other (and, I'll quote Rabbi Joel C.Dobin here),
Judaism's birth, however, was during the Age of Aries (you can find his article
HERE ) and yet, in the list that you have posted, it ruled by Virgo and, obviously, Mercury.
I am aware that it might sound as an extreme example of oversimplifying a very complex set of facts but, aren't all major religions (or religions in general), to a great extent described by Jupiter and Pisces (and, if you like Neptune). The transcendental mind, the after-life, the monasteries, the Unknown etc. ?!
But, back to the list! Do I find it convincing enough? I'm not sure I do, to tell you the truth.

If the general symbolics of the signs and their correlation with the general attitude or beliefs of the aforementioned religions is all that we have, I actually think that some of the facts do not make much sense to me. I am not a cultural anthropologist, of course, I am not deeply familiar with all of the religions mentioned in your list and I'm not a mundane astrologer after all, but, like many other people, I do have some general knowledge and I admit that, based on why I am familar with, some things do not seem logical to me.
I may sound like a total amateur

when I say this but isn't Virgo very descriptive of Christianity? (Virgin Mary, no premarital sex, ascetic life, fasting, immaculate conception, etc.) Or, is maybe Virgo the "co-ruler" of Catholicism? (Unlike in Orthodox Christianity and some other denominations, celibacy is still a requirement for ordination to the priesthood in the Catholic Church).
Surely, the "masculine principle" is very present in this religion too.
Also, for something as profound, complex and deep as a religious thought or teaching , the analogies such as
"the 6th sign/the start of David" ,
"the 8th sign/the Eightfold path" or the
12th sign/12 disciples to me seem a bit trivial (here I'm just sharing my personal impressions, of course.)
Not only do I find the idea of the number 6 being a reason enough to put Judaism under the rulership of Virgo/Mercury unconvincing (if of course, that was indeed the main reason to put it under the rulership of Virgo) but I also believe that all of these numbers could actually be applied to almost every religion mentioned above. And not only that, but I believe that there are numbers that are, at least in some cases, even more important than those mentioned in this classification.
Here are some examples: besides The 12 disciples, Christians also have the
Decalogue or
The 10 commandments (and so do Jews) and, again- in my head, this list seems to be even more representative of this religion than the 12 disciples (in terms of the religious teaching, its essence, the concept of the spiritual life etc.) . Also, there are
7 Capital Vices.
In Orthodox Christianity, the number Three carries a very important symbolics and some Orthodox Christians even insist on using three fingers when making the sign of the cross (
The Father, the Son and the Holly Spirit - and this is closely connected to the origins of this religion if not the most important fact; God exists and Jesus was his son and one cannot truly consider him/her self to be a Christian if one does not believe that it were so.)
Similarly, in Buddhism, the
8-fold path is a path but a path towards something higher and, in the Buddhist scripts, we can find other equally important lists some of which contain the very basics of this teaching. First and foremost, we have
The 4 noble truths (it all starts from there), then we have
The 6 realms ,
The 5 precepts,
The 12 links etc. Finally, number three is also very important because, when a person becomes a Buddhist, he/she actually takes refuge in the
Three Jewels or the Three Treasures (Triple Gem or simply Three Refuges) i.e. the
Buddha (the ideal or highest spiritual potential that exists within all beings), the
Dharma (teachings), and the
Sangha (community).
And so on and so on.
Similarly, I'm a bit confused by the choice of the main characteristics of each religion. Having mentioned Buddhism, and after seeing that Capricorn rules Confucianism (worldly advancement ), I'm not sure that, at least to me personally, Scorpio and the 8th look like the best representatives of Buddhism (And I am very much in love with the teachings of Buddha). Parinirvana, Nirvana, the sufferings listed under the 4 noble truths indeed do ring a few bells but it is worth mentioning that, though Buddhism is often labeled as "mystical" by the westerners, it is actually a non-theistic religion and the mention of suffering does not imply pessimism but actually optimism (it is all in our hands; no faith, no predetermination etc.) - Buddhism does not accept the idea that we are unable to overcome sufferings or that we are dependant upon the God's will - in Buddhism, the perfection lies inside of our own mind and it is the man (the individual) who is the central figure, not the God or Gods. Surelyt, pure (zen) mind correlates with the modern term of subconscious mind and no wonder Jung is often mentioned in the books about Zen Buddhism but, personally, I'm not perfectly sure if Pure mind and subconsciousness are best described by the 8th (i'm not sure if they have anything in common with the 8th), they sound like 12th to me and, technically, they are achieved (or can be reached) through the 9th (meditation has always been a combination of the 9th and 12th in my opinion, not the 8th; the 12th/subsonciousness via 9th/meditation and spiritual knowledge). Of course, we can say that the painful spiritual transformation (not that it is necessarily painful), the idea of reincarnation and so on correlate with the 8th but, at the same time, most religions assume that something happens after death (eternal life, Hell, Paradise etc.).
The conditioned arising or Dependent Origination i.e. the law of cause and effect that Buddhism is based on, is very "modern" and implies that we only have to obey to the laws of nature and it also includes a very rational approach that could be described by mercury too.
Assuming that perfection is hidden in every single human being that is so natural for Buddhism, might put this religion under the rulership of the Sun (individuality) and it is indeed a common thing to find parallels between Nietzsche's work and Buddhist scripts (especially Zen Buddhist teachings). It is also, in a way, applicable to the fact that the ceremony of lay ordination is not necessary in Buddhism (you can become a Buddhist at home) as well so, again- we have a strong sign of individualism. But, at the same time, we need to bare in mind that Buddhism, (like most other religions), stresses compassion (in terms of Buddhism, I believe that cancer is the best choice).
And, finally, this was the biggest surprise, I must say:
Taurus - Hinduism, ref sacred bull, showiness
I have been reading a lot about Hinduistic religions (and, the plural here might be very important since we are talking about numerous religions classified as Hinduism but by Westerners and not by the Hindu people)- but I am not familiar enough with their teachings to know if this classification would be acceptable to them. But it does look a bit strange to me. Hindu people are mainly vegetarians and they do not eat meat because they believe that a human should never kill another living being and that we can do just fine by eating plants and dairy products- for this reason, cows are highly appreciated and even holly animals (holly cow, aye?!

)- because they produce milk, and milk is very important in Indian vegetarian cuisine. But, Taurus likes to eat and when I think of a Taurean individual, i see a person who loves to eat everything, including meat. Now, as for the showiness, that i wouldn't know!
