Another follow-up:
====== Benjamin Lees wrote: "No, French Christians are just tagged with subcategories of Category:French Christians. The "requiring diffusion" category that you complain of is in fact a way to tell editors that pages in the category should really be in subcategories instead." ======
Aha! You're right, I had not realized that "diffuse" (disseminate/spread widely) was being used as specialized en-wiki-jargon for "subcategorize". It might be wise to give that hidden category a more descriptive name.
I looked into one of the many BLP entries with an unscourced Category:French Jews tag, and found a review of a book they wrote. In that book, the person stated that while they had a Jewish mother, they did not consider themselves Jewish.
Given that the category French Jews contains more members than the category French Roman Catholics, and that there are living people included in both categories... I seriously wonder what it is that motivates folks to anonymously tag others in this way (i.e. whether they want to be tagged or not).
The Library of Congress, the BNF, Wikidata, etc. don't label people according to religion, unless their notability is due specifically to their religion (e.g. Alfred Dreyfus, Maimonides, etc.). On en.wp people being labeled as Jewish/Catholic, etc. tend to be industrialists, politicians, journalists, bankers etc. I don't think this is "best practice" and I'm afraid I do not agree that en.wp is mostly "getting it right" with regard to this specific question. Fr.WP and Wikidata are doing much better.
The relevant section on "data subject" privacy rights in the GDPR (in English) is based on the 1978 French law I cited earlier (though it has become more restrictive since -- see below). As David Gerard noted, it is quite likely that this affects not only Wikipedians (who can petition to have libel/slander concerning their *online identity* (cf. definition of data subject) removed from (inter alia) block logs), but also the *content* of biographies of living people in the encyclopedia.
== GDPR (Article 9)==
*Processing* of personal data revealing racial or ethnic origin, political opinions, religious or philosophical beliefs, or trade union membership, and the processing of genetic data, biometric data for the purpose of uniquely identifying a natural person, data concerning health or data concerning a natural person's sex life or sexual orientation shall be prohibited.
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As one who has contributed to the projects since 2006, I am posting this here not because I wish to sow dissent, but because I think some quick thinking and corrective action is needed.
sashi