The past insistence that belief in one faith implies the total rejection of all others has given way, at least partly, to a ready acceptance of the fact that all depictions of the supernatural have much in common. Religions, however unique each one is now, often have significant links in the past. The etymology of Christmas is obvious: Christ + mass. The word christ derives ultimately from the Greek for "anointed"; it is related to the ecclesiastical term chrism, a consecrated mixture of oil and balsam used in anointing. The timing of Easter has been a contentious issue for centuries. According to the accepted formula, Easter is set as the first Sunday following the full moon that occurs on or next after the vernal equinox, March 21; thus, it should fall between March 21 and April 25. The number of days that the observance lasts differs between Israel and Diaspora and also, in the latter, between Reform and other denominations.