I just saw a discussion among corporate event planners where one person was upset that event organizers don’t give proper consideration to scheduling over top of Rosh Hashana and Yom Kippur.
I can appreciate the annoyance, when I was still a practicing Christian I would never think to schedule a work thing over Easter or Christmas. We should treat others with consideration, and should be mindful of what others view as important days. But I also don’t know what each religion considers to be major, non negotiable holidays. Do you?
Another question, does it matter where the event is? (for example, in the US should less consideration be given to holidays of religions that have fewer adherents?)
In fact no religion follows the Gregorian calendar, since that was invented by Pope Gregory in the XVI century, and by that time all of the major religions were already there. Christians migrated to the Gregorian calendar, but not everything, which is why Easter (which is also a Jewish holiday) keeps moving around on Gregorian dates.