The siel believe Zyi created the universe and their life spans, tying them all together in a gigantic invisible web called "the life thread".
Zyi spends their time tugging on the strings of each and every life, though their reasons are unknown. The siel believe Zyi simply does this because they are Zyi, and no other reason. The siel believe Zyi is both female and male and has many arms and legs - as many as there are people in the universe.
The siel do not worship Zyi as much as recognise them. They believe manipulating Zyi is pointless, and prayer is an attempt at manipulation.
Extremist Zyi worshippers often believe that sex without bondage and body modding is impure and against nature, a byproduct of siel culture being corrupted by mainstream galactic society.
Most Zyi worshippers do not share this belief, however, many non-Zyi worshippers lump them together with these much louder fanatics.