Well, ok, so maybe there isn't really that much controversy about the religious beliefs of fictional people in a (hopefully) fictional universe setting 1200+ years from now. But, it was asked (sort of), so, it shall be answered (sort of).
And if this post seems to trail off... it did... I got tired. So, if I seem to stop making sense somewhere in the Human religions section... suffice it to say that making sense of Humanity's religious tendencies is made all the more interesting in the early hours of the morning
We'll start with a quick overview of Alien religions, by species:
Aera:
The nature of the Aera homeworld never inspired much belief in any sort of loving deity. What began as a collection of local deities coalesced, through conquest by what was to be the dominant group on the entire planet, into a single pair of entites, one force of creation, and one of destruction, both abstract, and both uncaring. As time progressed, and the Aera advanced, these entities progressively lost entity status and drifted into the realm of spiritual concepts. Becoming more self-centered in their exploration of existence, destruction morphed into personal death, and creation into species survival. Organized religious activity among the Aera, such as it was, ceased centuries ago, but the impact on their culture of the concepts of death and survival is still quite strong. Indeed, Aeran mausoleums are said to be, quite possibly, the only pieces of Aeran art that might ever be considered beautiful. The Aera respect death, but value is placed on the accomplishments made in the face of one's imminent demise. All Aera are cremated, and the repositories for such remains are vast public works, filled with displays of the accomplishments of those entombed within, those who contributed greatly to the species being rewarded with physical space devoted to listing their deeds, and the rest consigned to a rotating schedule of intermittent holograms and access via terminal displays. It is in such places that an Aera would go to ponder, in silence and solitude, relenting briefly from the near tireless schedule of a short-lived species, the nature of its existence.
Bzbr:
Though the Aera have attempted to convince them to do otherwise, the Bzbr engage in hero-worship of the Aera. A majority of the Bzbr are convinced that the actions taken in this universe play out in other planes where the great nest of all life is threatened by chaos. They believe that the Aera, by having brought greater order to their lives, make them all great warriors in the other planes.
Dgn:
Dgn under Shaper control are officially prohibited from engaging in organized religious activities, as the Shapers believe it might foster solidarity among the Dgn, making them harder to control.
Klk'k:
The Klk'k frowned intensely upon organized religion even before they settled under the wing of the Andolians. Klk'k history had been rife enough with false prophecies and self serving church-like establishments that the Klk'k analog to the Enlightenment had been rather total in its sweeping reforms. Klk'k culture, however, has a long history of veneration of ancestors, which continues in various ritualized forms of behavior. There is no belief among the Klk'k that the deceased may be contacted, nor is there any particular spiritual nature to the reverance for those who came before, merely the conviction that it is one's duty to honor the fact that, without them, one would not be.
Lmpl:
All Lmpl are adherents of Rlaanbzztkrlbzeentkaan
Mishtali:
The Mishtali practice a number of religions, both native and foreign. Chief among the native religions in, albeit infamous, notariety, is the Cult of the Devourer. The Cult of the Devourer centers on the belief that success in life is directly tied with what one eats, and that the more powerful the being that was eaten, the better one's life can be. Thus, eating the remains of sentient beings is as good as it gets. This, obviously, raises a few issues among many groups, but there are enough humans and dgn willing to be paid for the eventual consumption of their corpse that the churches of the Cult of the Devourer tend not to lack for sustenance. These churches are, as a rule, very festive and pleasant places to visit, provided one is not turned off by the cuisine.
The Mishtali have been very willing to convert to just about anything, so the Mishtali also tend to have the largest Alien populations of most obscure human religions.
Nuhln:
All Nuhln are adherents of Rlaanbzztkrlbzeentkaan
Purth: The purth were pre-sentient before the Andolians altered them, and are universally predisposed to ignore religious issues entirely.
Rlaan:
Most Rlaan are adherents of Rlaanbzztkrlbzeentkaan. What this means is very difficult to say, as, though it is a text based religion, the text is under constant revision. Indeed, the Rlaan Assembly regularly submits changes and additions to the holy text. Contradictory edicts abound, and scores of companion volumes are included with every copy that debate the relative merits of breaking one set of edicts over another. Edicts contradicting each other,however, are the least of a reader's worries, as the universe is created 37 times in 17 entirely distinct fashions, by a grand total of 4301 entities, albeit 4210 of these were all in one creation story. History, morality, ethics, and the fundamental nature of reality itself are all presented in so many different forms in the text, that it defies rational understanding as to how the Rlaan consider the book canonical and relevant. However, they do. And they gather together at one of the 73 specified intervals of worship, for those that interpret worship as being allowed, to engage in whatever activity is currently believed to be both correct and legal by the group that has thus met. Rlaan places of worship are thus remarkably like most Rlaan art: constantly changing in nature but composed of themes that are themselves mind-numbingly repetitive, and constantly possessed of an aesthetic that runs counter to common human tastes.
Saahasayaay:
The dominant belief structure of the Saahasayaay revolves around each of them being an intruments of the great death god who sits in judgment over the universe. The Saahasayaay belive themselves to be the chosen people who alone are privy to the sentences being passed down upon the mortals of this realm. Saahasayaay prophet halls are built to express the joy of the hunt, the glory of the kill, and subserviance to the great death god. The prophet halls are built in keeping with the 3-dimensional nature of Saahasayaay travel, with perches on many levels, and rank denoted by attainment of a higher perch.
Shmrn:
The Shmrn have a spiritual existence quite different from their brothers the Dgn, with communal meetings contemplating the nature of suffering over one's lifetimes dominating the organized religious landscape. Shmrn culture and universe view centers on the principles that life is unfair and painful, but a necessary stage to receive the reward of eternal painlessness that awaits those who have, over several lifetimes, overcome their desires to avoid the unpleasantness of life.
Uln:
Growing up amidst the ruins of an exceptionally powerful and ancient culture on a planet where life was artificially introduced gave the Uln the idea that they were the children of failed gods. Convincing them that they are much more likely the descendants of lab-monkey-analogs from a long destroyed outpost hasn't gotten very far. What passes for organization in Uln religion involves seasonal festivals that mostly serve to reinforce the doctrinal line that being born Uln is a wonderful thing, relative standard of living to the other species be damned.
and now, HUMANITY!
By major group:
Andolians:
The linked existence and general culture proclivities of the Andolians have brought them to near unity on their religious doctrine. While an Andolian would refer to his/herself as a devout skeptic existing in the absence of proof of the metaphysical, many others find it simpler to call them Atheists.
Forsaken:
The forsaken are split between those who, in the face of great suffering, clung to their religiosity, and those who abandoned it utterly. Many of the relious groups among the forsaken are virtually unchanged in practice from their forebears centuries ago. Religions that came into popular membership after humanity took to the stars are looked upon quite poorly by both the religious and the non-believers alike. Tolerance for and among pre-existing groups, however, is quite high, as centuries of mutual need have eroded the barriers imposed by doctrinal difficulties. In general, the religious life of the Forsaken greatly resembles that of a more peacable late 22nd century Earth.
High-Born:
The religion of the Highborn is the bastard child of Calvinist WASPism and Objectivism, marinated in a counter-historical romantic view of the importance of chivalry and the duty of the better to the wretched.
ISO:
Good trotskyites all, they've stuck with the whole Marxist "Opiate of the masses" take on things.
LIHW:
Just about anything you can think of is practiced somewhere on some planet in the LIHW.
Luddites(Interstellar Church of True Form's Return):
Beginning as an extremist faction of the Purists, the luddites are the most powerful religious terrorist group, not that there are many competing for that title. Both members and the church hierarchy are, by and large, true believers, and, while no luddite base lacks accomodations for worship, most tend towards a certain modesty. There are, however, notable exceptions - those facilities built specifically for the glorification of the 'Lord God, Creator, Maker of Man in His Image, Guide to the Return to Our True Form', are quite striking.
Mechanists:
Mechanists practice many different religions, some more suited to hatred of one's own body than others.
Merchants:
Worrying about religion gets in the way of making money. This doesn't mean that the Merchants aren't practitioners of various religions - they just don't worry about practicing them on Guild time.
Purists:
Purist society encompasses a plethora of religions, but the only ones with many adherents are those that agree that man was made in the image of his maker - and should stay that way.
Shapers:
Shaper philosophy tends towards anthro-centrism. The only authorities a shaper sees fit to answer to are his/herself and the species as a whole. Religious behavior is seen as weakness and running counter to one's useful wills.
Unadorned:
The unadorned worship logic. Moreover, they worship the logic of machines. Their society and public works reflect this. Admittedly, most other groups think them slightly mad, but the Unadorned find religious veneration of computational logic entirely... logical.
Certain major players otherwise expected to have gained many adherents through proselytizing and/or uncontrolled birth rates either had the misfortune of settling worlds not part of the jump network, having their colonies wiped out by the nano-plague, or being otherwise relegated to a marginalized role by not having left earth before the nano-plague and not surviving the cultural chaos as dominant forces. In general, however, the lack of religious dominance in human space by any particular set of groups is due to the way in which humanity went to space - balkanized, and disagreeing with itself at nearly every turn.
