A few years ago, Rav Yonasan Rosenblum wrote a piece on how Shavuos, in contradistinction to Peach and Sukkos, is essentially an Orthodox-only holiday:
Matan Torah is the most important event in human history. Had our ancestors not accepted the Torah, all of Creation would have returned to its original formlessness. Yet most Jews Shavuos have barely heard of Shavuos, the celebration of Matan Torah. In Eretz Yisrael, the contrast between Shavuos and the other yomim tovim could not be more stark. Most Jews celebrate Pesach and Sukkot in one form or another. Almost all families sit down to a Seder. And even in non-religious neighborhoods, many families build sukkahs. On Yom Kippur, the streets fall largely silent, and a large majority of the population fast. In short, the rhythms of the Jewish calendar are felt.
While the situation is not quite as dire in North America - many non-Orthodox communities in larger centres have all-night learn-a-thons, for example - the contrast is there. For all Orthodox Jews, Shavuos is on par with Pesach and Sukkos. Perhaps it's even more appreciate as it involves the least tirchah to prepare for. For the non-Orthodox, it's only selectively known and enthusiatically observed.
There is, however, another day in the Jewish calender that is observed universally by the Orthodox and ignored by most of the non-religious: Tisha B'Av. The reasons for this are simple. Most non-religious Jews don't realize the gap in the religious lives that the absence of the Temple (may it be speedily rebuilt) brings. In addition, the timing of the holiday, in the middle of summer vacation, isn't very pragmatic. As a result, while frum shuls are filled for the reading of Eichah, outside of the Ramah camp system and larger synagogues in larger centres, most heterodox communities let Tisha B'Av pass with nary a murmer.
What is the connection between the two? The Jewish Week, in its latest editorial piece, would like to look at Shavuos as a holiday of Jewish unity:
One powerful message of Shavuot (May 29-30) is that despite our differences in observance and ideology, we share and treasure the same Torah. The concept of one God, the 613 commandments, the notion that each of us is created in the image of our Creator, the weekly observance of Shabbat, along with other key elements, however we may interpret them, are a revealed legacy of the encounter between God and the Jewish people at Sinai.It is important to remember this bond at a time when we are concerned about our shrinking numbers and when divisions among us make headlines. Rabbi Norman Lamm, the chancellor and former president of Yeshiva University, caused a stir in recent days when he asserted in an interview with the Jerusalem Post that the liberal branches of Judaism are disappearing. “With a heavy heart we will soon say Kaddish on the Conservative and Reform movements,” he said. “The Conservatives are in a mood of despondency and pessimism,” he added. “They are closing schools and in general shrinking.”As for the Reform, they “may show a rise because if you add goyim to Jews, then you will do OK,” a reference to the movement’s decision to include as Jews children of patrilineal descent.Such words are not only hurtful, but at odds with the notion of Klal Yisrael, the unity of the Jewish people, that Rabbi Lamm has championed throughout his proud career. What’s more, they fly in the face of statistics showing that nearly 80 percent of American Jewry is made up of Conservative and Reform Jews.It is true that Orthodoxy, once consigned by experts to extinction, has grown in recent years, strengthened by ideological conviction and large families. But Rabbi Lamm has been among those who consistently warned against triumphalism among the Orthodox. Part of the problem with the divisions among us is that both traditionalists and liberals seem to be convinced, at times, that the other cannot endure, so why bother to reconcile?The festival of Shavuot, underscoring the one Torah we all hold dear, and its theme of Ruth, the true convert from whom, we believe, will come the Messiah, reminds us that each Jew is precious. We can disagree among ourselves, with respect, but our motive should be compassion, not defeat.
While these are special words, they are also full of fluff. The real message of Shavuos is not about Jewish "unity" but that 50 days after yeztias Mitzrayim God Allmighty revealed Himself to us at Har Sinai and gave us His Torah, re-branding us as an am segulah.
In the many millenia since then, Matan Torah has had a repeatedly rough time of it. While the cloud of God still covered Har Sinai above them, the eirav rav coerced Aharon HaCohen into making the molten calf. Is it any wonder that today Sinai Denial is still in full swing? Indeed, within Reform and Conservatism, it is quite standard to accept the Documentary Hypothesis and deny the revelation at Sinai. You're considered either a fanatic or hopelessly naive if you insist that God spoke to Moshe Rabeinu, a"h.
As the editorial notes, each Jew is indeed precious and that despite our disagreements we must remember that we are one giant family whose love for one another must be paramount. But what unites us as Jews cannot be some airy fairy concept of tikun olam in the form of ecofascism or a common denial of the basic tenets of Chrisianity and Islam, but rather an acceptance that we are a people founded on, immersed in and sustained by Torah. Otherwise, if one denies the significance or even the occurence of the event that it is based on, what is the point of observing Shavuos?