If I created a religion, I would probably not call it such. I would probably call it a mindset or a philosophy. There exists a sort of stigma about religions that I don't necessarily want to deal with when there are more important points that I could be discussing.
For instance, the Oxford Dictionary defines religion as "the belief in and worship of a superhuman controlling power, especially a personal God or gods," or "a particular system of faith and worship." However, I quite like how Dictionary.com defines it, "asetofbeliefsconcerningthecause,nature,andpurposeof the universe,especiallywhenconsideredasthecreationofa superhuman agencyoragencies,usuallyinvolvingdevotionaland ritual observances,andoftencontainingamoralcodegoverning the conductofhumanaffairs."
The belief in a higher power seems to be rooted in the word, and while a religion doesn't necessarily propose belief in a god, I feel that a philosophy or mindset would be more apt to the nature of what I would create.
Of the first principles, I would propose that I, being human, am a completely fallible being. I am an animal just like all the rest of us and therefore I can make mistakes. Nothing I write should be taken as law and indeed should be challenged like any other theory. I also recognize that some of the principles I propose cannot be proven or even tested, thus they should be taken with a grain of salt.
Most importantly, if I created a religion, it would be inclusive and its ultimate goal should be to help the human ecology thrive. I believe religion has the ability to do good for humanity, but the prominent religions are becoming increasingly outdated and are slowing growth and prosperity for some. I don't necessarily feel like there exists a need for a new religion, but I feel compelled enough that I could be confident in proposing one of my own. Not that it would gain any traction.
One of the more important tenants of my religion would be acceptance of different beliefs regarding a big G god. That choice would be left to the individual. We can't know if there truly is an almighty deity, so there's simply no need to fight over something that cannot be proven. Theists have their merit in that no one knows what happened before the Big Bang. Perhaps the Big Bang is evidence of an unmoved mover, perhaps the answer lies somewhere in space. We do not yet know.
However, I know a major holdup of my religion would be the proposal to ditch terms and practices that are predominantly present in the West. Worship should not be required, but instead an individualistic form of practicing faith. Religious institutions should not be tax exempt and should not be able to contribute to political campaigns. Concepts such as funerals need to be revisited to accommodate the limited amount of space we have on our planet.
If I created a religion, I would do so in the hopes that humanity can survive beyond the death of our solar system. While death may be inescapable, we owe it to the future of our kind to prolong life as much as we can. Until the universe dies out, humanity shall be among the stars, thanking us for not killing the planet while we still inhabit it.