In Shemot 19:v.2 the Torah states, “They camped in the wilderness, and he, Israel, camped there  in front of Mount Sinai.” Rashi asks why it says, “he… camped” in the singular when there were millions of Jews in front of the mountain. Rashi explains that we all united “like one person with one heart” in order to receive the Torah.
 
At the Sinai Revelation, "the people all responded with a single voice, "We will keep every word that the Hashem has spoken'" (Shemot 24:3).  Was this a one-time phenomenon, in which every Jew was identical to every other in his conduct and thought, an ideal situation?  Alternatively, might it not be that beyond every Jew's obligation to fulfill the 613 Mitzvot and to believe in the tenets of Judaism, the Jew has a variety of options regarding how to live a life of faith?  Seemingly, Israel's division into tribes and the differences between the activities of each are the proof that there exist a variety of options for how the Jewish People must conduct themselves in Eretz Yisrael.  Amongst the various tasks is that of serving G-d exclusively, and that task was assigned to the tribe of Levi.  As Rambam wrote (Mishneh Torah,Hilchot Shemitah 13:12):
 
"Levi was set apart to worship G-d and to serve Him, and to teach His upright pathways and His righteous laws to the masses, as it says, 'They shall teach your law to Jacob and your Torah to Israel' (Devarim 33:10)."
 
But Rambam adds that this tribal role does not prevent any individual on earth who is so motivated, from following in Levi's path and dedicating his life exclusively to learning and teaching Torah.  The tribal "togetherness" mentioned in Devarim 33:5, “And it was when there was a King in Yeshurun; when the chiefs of the people gathered; together the Tribes of Israel” is referring to unity, not uniformity.  In Berachot 35b, Rabbi Yishmael and Rabbi Shimon Bar Yochai debated regarding the respective roles of work versus Torah learning.  Rabbi Yishmael derived from the verse, "Gather your grain" (Devarim11:14) that a person must combine work with Torah learning.  In response, Rabbi Shimon bar Yochai asks, "[If everyone performs all the seasonal agricultural tasks required], what will be with the Torah?"  In his opinion, the ideal person must trust that his agricultural tasks will be done by others.  The Talmud then quotes Abaye, "Many followed Rabbi Yishmael and were sucessful.  Many others followed Rabbi Shimon bar Yochai and were unsuccessful."
 
Rabbi Tzadok HaKohen of Lublin, in his book, "Tzidkat HaTzadik" links the debate between Rabbi Yishmael and Rabbi Shimon bar Yochai, and Abaye's conclusion, to the differences between the first two paragraphs of the Shema.  The first paragraph of the Shema is in the singular, the second is in the plural.  The first parsha says that we must love G-d "with all our might" (Devarim 6:6) which the Talmud explained to mean all our wealth.  The second paragraph, “And it will be if you will listen…” has no such phrase.
 
Rabbi Tzadok derives from this that the first paragraph in Shema,written in the singular, is addressed to special individuals who receive a divine calling, such as Rabbi Shimon bar Yochai.  That is why they are required to love G-d "with all their wealth."  Such individuals are required to abandon even their livelihoods for the sake of serving G-d.
 
By contrast, the second paragraph was worded in the plural and made no mention of sacrificing one's wealth, and referred to one's "gathering in his grain".  As Rabbi Tzadok explained, this was because the masses "must work, and they must supervise their wealth and worry about earning a living and supporting themselves."  According to Rabbi Tzadok, the reason that many followed the path of Rabbi Shimon bar Yochai unsuccessfully was that "such is not G-d's will.  In this world, G-d wants man to cultivate the world and not to leave it desolate."  From here we see that there is one demand made of the elite Torah Scholar, and still another from the general public.
 
In Parashat Ekev (10:12), the Torah asks a question:  "Now, Israel, what does the L-rd your G-d want of you?"  The Netziv, Rabbi Naphtali Tzvi Yehuda Berlin, in his commentary, "Ha'amek Davar," explains that the Jewish people comprise four groups and G-d asks something different of each group.  The first group are Israel's heads and communal leaders.  The second are the Torah scholars, who are called "the elders of Israel".  The third are the people who work for a living, and the fourth are the children.  Regarding the four groups, the Netziv writes:
 
"Each of these four groups differs from the rest in what G-d asks of it.  G-d does not ask of all of Israel, but rather of each individual Jew in accordance with his stature…That which G-d asks of one He does not ask of another.  And sometimes what He asks of one group is almost forbidden to the second group.”
 
There the Netziv elaborates on what is demanded of each individual group.  He states:  "As far as laymen working for a living, they must keep the mitzvoth in the time available to them and their business must not nullify any mitzvah.  Yet it is impossible to ask of someone preoccupied with his business affairs to envelop himself in the love and fear of G-d.  You can only ask practical mitzvah fulfillment, and that is what G-d asks of them."
 
Regarding the principle that there can be separate but equal pathways to serving G-d, the Chafetz Chaim derives this from Ta'anit 31a:
 
"In the future, G-d will hold a dancing circle for the righteous, and He will sit in the middle of them in Gan Eden.  Each of them will point with his finger, saying, 'This is our G-d, for whom we waited.'  (Isaiah 25:9)."
 
The Chafetz Chaim comments:
 
"If one uses a compass to make a circle, then from any point on the circle, the distance to the center will be the same.  Likewise, there are many pathways to serving G-d.  Any pathway by which one truly and sincerely longs for G-d and seeks Him out will be the equal of any other.  Thus, in G-d's dancing circle, the righteous will dance around G-d from different sides and each will point at G-d with his finger.  Each righteous person will be equidistant to G-d."
 
The Chafetz Chaim was addressing those righteous people and those scholars that think that they alone are close to G-d.  In the Messianic Era, it will become clear that many approaches are equidistant to G-d. Thus, the message of Shavuot is that one should accept and love all Jews and not judge them harshly.