Elements of a Successful Galactic Religion

If extraterrestrials ever arrive, they might be interested in the physical conquest of our planet. Or conceivably they might be interested in spiritual conquest. Their purpose in coming might be to spread some strange alien religion to distant spots in the universe. But if they were trying to do that, what type of religion would have a good chance of being successfully spread to distant parts of the galaxy, given sufficient enthusiasm in those who were spreading the religion?

To answer that question, we should first look at what type of religions would tend to be very hard to spread across multiple solar systems. It would seem that the hardest religion to spread to many other planets would be one that was highly location-oriented. I will give an example to explain what I mean.

Imagine a spaceship were to arrive on our planet, and extraterrestrials were to come out of the spaceship, aliens who had mastered our language. Imagine that they were to begin expounding a strange alien creed, with some type of pronouncement like this:

Learn, little Earthlings, the glorious deeds that occurred 9,400 years ago on the distant planet Arzurus. On the continent Zynora in the land of Telsun there walked the great prophet Olnor, who received the holiest truths ever revealed. Many a miracle did he work back in those days, proving the truth of his supernatural claims.

Would a large fraction of the world's population be likely to give up their religious beliefs, and adopt this strange new creed? I don't think that is likely.

This strange creed would not be very suitable for spreading to many distant solar systems, because it would be so location-oriented. Someone on some other planet would hear about these events on the planet Arzurus long ago, but these events would probably seem very distant and remote. A person on our planet would react to such a narrative perhaps no more warmly than the average person reacts today when he hears about the discovery of some distant galaxy from the earliest ages of the universe. The events would seem so remote and distant that it would be hard to incite the fervor typically associated with the successful spread of a religion.

But what type of religion might have a relatively high chance of being spread across multiple solar systems? Perhaps it would be one that was more universal, some creed that was not centered upon events occurring on one particular planet, but on truths or principles that make equal sense on any planet.

I can imagine some elements that might be parts of a successful galactic religion. Such a religion might have one or more of these elements.

A belief in some God of the universe. A galactic religion might tend to be more successful if it preached some gospel of a universal deity, not some deity who seemed to have his attention focused on one particular planet. Such a doctrine could be supported by a discussion of fine-tuning in physics and cosmology, involving fundamental physical constants that are the same to all observers in our galaxy.

A belief in some universal mystical force. We can plausibly imagine a successful galactic religion that is somewhat akin to the Jedi creed in the Star Wars movies, with a belief in some universal force that an individual on any planet can somehow access and use to his benefit or enlightenment. 

 
A belief in some interplanetary brotherhood or interplanetary communion of minds. The life forms living on different planets might be tremendously divergent in their physical appearances, but conceivably some successful galactic religion might attempt to dissolve these differences, by describing some basis by which all life-forms can be considered brothers or kinfolk, or describing some means by which distant life-forms can somehow commune with each other, possibly through some type of instantaneous mysticism.

A belief in some higher destiny or state of evolution towards which individual life-forms can strive. An element in many a successful religion is the idea of progression, wherein the individual progresses to some higher state of being. We can imagine all kinds of futuristic galactic permutations on this theme, including evolution to a state of superintelligence, evolution to a state of pure energy, evolution to a purely electronic state of existence, and so forth. One of these might be an element of a successful cosmic religion, with the progression being described as some glorious destiny to be achieved, perhaps a little like the Buddhist ideal of nirvana.

A belief in some immortality that can be reached. Besides supernatural concepts of life after death, a successful galactic religion might have any number of technological descriptions of immortality, similar to those we already see developing in transhumanist circles, which imagine people becoming immortal through breakthroughs in medical science. 
 
A belief in some paradise or awesome state of organization towards which societies can strive. Christian theology has postulated some future millennium to be achieved by divine intervention. A successful galactic religion might imagine some desirable state of existence to be achieved by galactic societies, perhaps involving the godlike mastery of matter in particular solar systems, or perhaps involving the establishment of some kind of galactic empire or society of planets or a cosmic Utopia.

Rituals, stories or architecture that evoke awe and wonder. Earthly religions have evoked awe and wonder through stories of miracles, and through music and awe-inspiring architecture. Having the whole grand stage of galactic evolution and countless planets to work with, a galactic religion might find it easy to evoke far greater awe and wonder. It might include far-flung tales a hundred times more wondrous than the story of the parting of the Red Sea, and it might have rituals involving all kinds of high-tech ways to stimulate the emotions of the faithful (including electronic brain stimulation, virtual reality, and mind-expanding drugs). The religion might involve soaring robot-created architecture a hundred times grander than the Notre Dame cathedral. 

A belief in some universal ethic. Some ethical precepts make sense at some times, but don't make sense in other times (I can think of the example of “Go forth, and multiply,” which makes sense until you have a population explosion.) A successful galactic religion might preach some universal ethic that would make equal sense in all centuries and on all planets. Such an ethic would not necessarily be radically different from some precepts of successful Earth religions. I'm not sure there's any fancy cosmic rule that might improve on the Golden Rule: do unto others as you would have them do unto you.