France owns it. Nationalized during the Revolution and for a few years a secular building, the Home of Reason or some such silly name. Napolean I restored it to the Catholic Church. Don’t know if actual ownership changed or he just restored the use, but if it did at some point the French Government regained ownership and leased it to the Church. Making it a secular “monument” makes as much sense as making it a Mosque. Which I’m sure will be suggested. Maybe just a corner.
Cult of Reason, just as silly but at least they recognized the Revolution was a cult.