Is it normal that i dislike to study one topic as a science, but do another?

You are incorrect, you have significantly changed the meaning in the two examples cited.
In the first instance, the reader might ask questions and actually learn something.
For instance: Who is she? How did she become a professional? How does she play [musical style] the musical instrument? What genre of music does she play? What is a piano? How does a piano work?
Then, by adding the -ist suffix to piano, all that you have said is that she is a professional piano player. You then re-affirm this by stating, she is a professional piano professional. We then form an opinion of what a professional piano player is. We all know what a professional piano player is, but can you define it? Now ask questions. Who is she? Answer: She is a professional piano player. How did she become a professional? Answer: I don't know, she just is. How does she play the musical instrument? Answer: Professionally. What genre of music does she play? Answer: she plays the genre of music that I, most or many other people enjoy, of course. The last two questions are invalidated. We are now not discussing a piano, but a piano professional (unless the reader makes the connection).
In the second instance, the reader might ask what the Shinto belief is. In the second part, you have made a statement that there are practitioners of the Shinto belief, and that there are variants in this.
This (the use of -ists and -isms) often leads to argumentative and sometimes hostile behaviour.

I dispute your statement that [the use of -ists and -isms], "are perfectly valid as a vehicle of thought." What these usually end up doing, is causing us to become argumentative and hostile towards one another. It also often leads to too much thinking and not enough doing, sometimes at great expense. This also contributes to the many divisions in society.

Some of the thoughts, ideas or concepts within these various -ists and -isms are perfectly valid, but the validity of these [-ists and -isms] in themselves are not.

Now, you have previously stated that you are an advocate of an ideal. Would you be able to please describe this ideal society to me or anyone else? Do you have any academic credentials in this regard? You also stated that you learned this from your parents. Do (or did) your parents have any credentials or expertise in this?

I would like to coin a new phrase and term at this time (this is somewhat derogatory, but should be taken lightly with a sense of humour),
"You are fullovists" etymology: full + of + -ist

My personal philosophy, like many, is influenced by many things in my life including my family, the culture I grew up in, my spiritual beliefs, and my life experience.

To wittle it down to the basics, I believe that success in life is a subjective term. As long as I am happy and as long as I am not causing pain or strain on those around me, I am successful.
By my philosophy, I also believe in helping out others find a place where they can be happy.
I'm pretty open to non-conventional views. (Lack of higher education =/= failure for one.)
In other words, I hold some high ideals. Those ideals are mostly about acknowledging the individual (I want to say individualism so bad...) and how one does not have to follow what is typical to find thier way. On a more personal level, it's about finding happiness no matter the position you find yourself in. I have a problem with mental depression at times, so that last one is very important.

Is that a little better?