The Sune embrace 'Naturalism' heavily in culture and belief. Typically they do not hold the concept of a 'supreme being' or grand pantheon, rather they (or at least those that practice) believe that the natural cycle of life affects personal destiny and touches facets of the universe. This is, of course, heavily cliff-noted but the modern Sune religion isn't that special or deep to begin with as most of the population is typically agnostic. The rate of technological advance and sophistication has, for the most part, granted Sune the peace of mind and order archaic religions claimed to provide.
The modern Sune religion is generally split between two sects: Aura Sirutic and Aura Ganist. In Sune linguistics, Aura means either Legendary, Great, High, etc. Sirutic is a denomination of the old term Siru, meaning Mother, Surrogate, Caretaker, etc. Gan is a more recent phonetic meaning 'Land'. As such Aura Siru means 'Great Mother' and Aura Gan 'Great Land'. Both obviously worship their respective term.
Aura Sirutic is an evolution of the old word 'Aursiru'. As mentioned above, Sune believe strongly in natural forces as opposed to the supernatural. The belief in the Great Mother is more to do with paying respects to this figure. Actually, more specifically, most Sirutic scripture is mournful and expresses deep loss over the Great Mother. Sirutics pay great love and attention to this lost figure, however nobody really knows who this Great Mother is. As per Sune naturalism, the Great Mother figure is mostly akin to what we'd know as 'Mother Nature', or the cycling of life.
Aura Gan is an evolution of the old word 'Aurigan'. Ganists are typically Sune with a more adventurous outlook on life as the scripture pays especially close attention to a great land host to the Sune now lost to time but waiting to be discovered. This lost holy land is described as being a paradise beyond description, whilst the Sune having wandered then lost their way from. It plays strongly to the ideal of finding or creating a better place.
Though not necessarily a sect of its own, both sects of Aura play mention to the 'Invisible Fathers'. Some had dismissed it as the obvious counterpart to the 'Great Mother' of Sirutics but the phonetics differ, translating the adjective to something more like "Mysterious, unseen, invisible, intangible" rather than Legendary or Great. The everyday Sune typically handwaves this off as a warning to parents to never abandon their children.
As typical with the generational problems with religion, it's not an easy topic for archaeologists to go over. However historians have noted that modern Sune history only dates back 2000 years with absolutely no fossil record from before that. Coupled with these 2000 year old scriptures that make great mention of 'Lost Lands' and 'Lost Mother', most historians feel that these old Sune at the start of record had felt emotionally depressed at the loss of something important... Or rather these literature make great mention to the importance of having to search for something.