Around the time of Christ, this difference caused a huge rift between Rabbanite and Karaite Jews. But these days, many Jews have not even heard of Shavuot. In such times, wouldn't it be wise to broaden our horizons a little and welcome the Karaites into the greater Jewish community... even if they celebrate Shavuot a little later in the week?
The thriving Karaite community in
I am reminded of a mishna every Jew should know:
Beth Shammai permit the [rival wives] to the surviving brothers, and Beth Hillel prohibit them... Though these forbade what the others permitted, and these regarded as ineligible what the others declared eligible, Beth Shammai nevertheless did not refrain from marrying women from Beth Hillel, nor did Beth Hillel refrain from marrying women from Beth Shammai. [Similarly...] neither of them abstained from using the utensils of the others for the preparation of food that was ritually clean. (Y'vamot 1:4)
*The intricacies of the debate are far too boring to go into here. All interested parties should start with Leviticus 23:9-21 and Joshua 5:11. The interested Rabbanite should proceed to the Babylonian Talmud (Menahot 65a-66aa); the interested Karaite to the Korner. The Modern Orthodox movement has prompted much more in-depth learning of Hebrew Bible, and this has re-opened a very interesting debate about literal (p'shat) vs. exegetical (d'rash) understanding of the Torah. Historically, a chasm has developed between Orthodox Jews and the Karaites and Samaritans. Perhaps this newfound appreciation of "p'shat" will lead back to a reunification of sorts.