linguistic confusion with the word 'atheist'

[Beka]

I was thinking, that many people may be confused on what atheist because of its construction. I think it is wrong.

For example, the Spanish word for atheist is ateo not
ateista like budista (Buddhist)

This is what -ist means according to wikipedia:

-ist is an English suffix denoting a person - it describes that person's chief duty, or belief. For example, a socialist is a person who believes in the tenets of socialism; a sexist is a person who believes that one sex or gender is superior to the other; and a receptionist is a person who performs duties in the reception area of an office. Other examples are listed below.

It is closely related to the suffix -ism, though there is not a one-to-one relationship between them. For example, there is vandalism but not vandalist, and canoeist but not canoeism.

Curiously 'atheist' is listed as an example which I disagree.

In my opinion an atheist is someone who does not believe as oposed to someone who "believes in not-believing"

P.S. I think this is more relevant here than in CL