First Appearance: (mentioned) Squadron Supreme (vol. 1) #1 (Sep. 1985)
Creators: Mark Gruenwald
Number of Appearances: 1
Note: Earth-S counterpart of Inhumans; never had Terrigen mist
The "Utopians" of "Earth-S" (or Earth 712, the world of the Squadron Supreme) are that world's counterparts to the Inhumans. The Utopians never discovered Terrigen mist, and thus never began exposing themselves to the mutagenic mist which transformed their bodies in unpredictable ways and bestowed super powers. The Utopians thus developed a radically different culture and religion than mainstream Marvel Earth's Inhumans.
The best known Utopian is Zarda, also known as the super-hero "Power Princess." She is, in many ways, here world's analogue to DC's Wonder Woman.
The other Utopians left Earth following World War II because they wanted to avoid a nuclear war.
Obviously the idea of "Utopianism" is embodied in the name the Utopians chose to be known by. The extent to which the Utopians can be regarded as "Utopian" with regards to their philosophical and/or religious identity is a topic that needs further exploration. Presumably careful study of Power Princess (Zarda) and her beliefs would be the best way to glean information about the beliefs and religious practices of her people. The other Utopians have apparently never actually been portrayed in comics.