From the helpfile for designing a tribal/nomad concept:
"Does your tribe worship anything? Do they have an enduring set of myths or gods? Do they believe in spirits?"
From "Creating a Magicker":
"Although it is acceptable that a character thinks of their element as a god or supernatural being, you may want to go for something a little bit more original."
Helpfiles speak to the players, and the references players would have. 'It is acceptable to use the player's understanding of what gods are to form the opinion of what a PC thinks of their element, as a magicker.' Similar case for tribal PCs and their tribes.
For city based PCs it isn't spelt out as well. However, there are no unique qualities that prevent Utep and Tek from being the figureheads of a religion. There are religions that are nontheistic, IRL. There are religions with no afterlife. There are religions with living, breathing beings you are meant to worship or practice for. There is even a religion for something everyone knows is fiction, Jedi.
The idea that that they can't be part of a religion requires redefining the term from how scholars and governments use it. If staff doesn't want us to use them as a religion, seems like it, then it is way more simple to just ask that we don't.