Answer:
Scientologists would believe that you are a life-force, that life entity that animates the body. There are many words for this such as spirit and so on.
Scientology itself is about the laws that govern this life-force and spirit and how by knowing and using these laws of life you can be bettered. They are not the same as physical universe laws. This knowledge of life's laws is important as then you be in control of life instead of affect of it.
The practical side of Scientology is about using this knowledge to help yourself and others.
The closest cousin to the Scientology belief would be Orthodox Buddhism.
While Scientology is not a belief system, it does allow you to rationally work out things and then project that workability onto different problems. There is really no blind faith in Scientology. None at all.
If Scientology is real for you, then it is. If it is not, then do not say it is. This is personal integrity in Scientology. Do not say something to be true if it is not.
But in reading your question I would think you might want to know - what do Scientologists come to understand to be true after doing Scientology?
Each Scientologist would answer this themselves from their own standpoint in Scientology. Scientology teaches you how to work out life's problems using the philosophy of Scientology, and how to make yourself more able. So you could get many thousands of different answers to this question.
But I will tell you my own understanding after 25 years of Scientology.
I understand that I am a spiritual being, more than a body.
I understand that my integrity is very important to me.
I understand that I have memories going back well before this life time.
I further understand that the body also has a set of memories we call the reactiove-mind and that they go back the nine months before pregnancy and this is the subject called Dianetics.
I could overload you. But I hope this is enough. The links show more.