In Scientology, basic beliefs of the Scientology religion are publicly available to anyone, in any one of the eighteen basic books of Dianetics and Scientology and the 280 lectures going along with them, in every Church and Mission of Scientology worldwide. Also in public libraries, internationally. This material is so easy to get, read and listen to, it hurts. Scientology founder L. Ron Hubbard wrote in his books and spoke in his lectures about the origins of the Universe, the questions of Man’s relation to a Supreme Being and the Creation theory (called “The Factors”) of the Scientology religion. No secrets, nothing. Just plain, public books and lectures. Xenu, Xemu or Zenu are not mentioned, part of or hidden in the core beliefs of Scientology. Nope. Also, Scientologists do not pray to or worship somebody called Xenu, Xemu or Zenu. This is a myth.
A note for the sceptic:
Scientology is done step by step. You are not given all the scriptures in one fell swoop and told to read them. You learn basics, then you learn more intermediate data, then there is more advanced information. This is not unique to Scientology, see the Scriptures Chapter. It is a central belief of all Scientologists that people must be properly prepared -- spiritually and ethically -- to receive these materials and that premature exposure would impede the spiritual development of individuals so exposed, an outcome that is inimical to the goal of Scientology -- the achievement of spiritual freedom for everyone living on this planet.
There are not many such scriptures. A number of years ago some confidential Scientology materials were stolen, altered and released by admitted enemies of the Church. There is no complete "OT" or "OT Level" information available on the internet but only altered and perverted data.
As Scientology is done on a gradient, and OT Levels are considered to be upper level, and confidential, a great many (close to 95%) of Scientologists have never read this information. The confidentiality is because this information, gotten into the wrong hands and perverted (as has happened) can cause a great deal of upset and misunderstanding. Scientologists do not discuss this information as they have been asked not to.
BUT - all this nonsense that this uppper level material would contain a "Creation Myth" or something is. not. true. These scriptures do not contain core beliefs of Scientology. Those are - as I said before - openly available.