Moses had divided the people of Israel into several classes of holiness: the "ordinary" Israelites, Levites, Kohanim ("priests") and, at the pinnacle, the Kohen Gadol ("High Priest"). The Israelites — the farmers, merchants, craftsmen, soldiers and statesmen — were to pursue the "normal" existence of life and vocation. The tribe of Levi, however, was distinguished by G-d to serve as spiritual leaders and priests. Within the tribe of Levi itself, Aaron and his descendants were consecrated as "Kohanim" and entrusted with the primary role in serving G-d in the Sanctuary. Aaron himself was appointed Kohen Gadol in this holiness hierarchy. Korach rebelled against this spiritual elitism and seemed to desire the office of high priesthood for himself.
Korach comes across a champion of equality, railing against a class system that categorises levels of holiness within the community. Yet, in the same breath, he contends that he is the more worthy candidate for the High Priesthood than the privilege of serving the priest as a Levite.
The Lubavitcher Rebbe analyses Korach’s arguments, motives and spiritual profile. Korach's failing was twofold: that in regard to his own self, he had the desire but lacked the commitment (a state analogous to being "consumed by fire"); and in regard to what he was advocating, he saw only the commitment, and not the desire (a state analogous to being "swallowed by the earth").
Moses makes a speech to try and calm the rebellion, suggesting it was not he who ordained the holy ranking but a higher authority (with a capital ‘H’), and that would be proved “if the Lord creates a phenomenon so that the ground opens its mouth wide and swallows them and their property and they go to the grave alive, then you will know that these people have provoked God.” When Moses finished speaking the ground under Korach and followers split, and the earth swallowed them, their houses and their property. Then a fire went out from G-d and it consumed the two hundred and fifty of Korach’s followers.
The next day, the whole Israelite community railed against Moses and Aaron. This time, it is G-d himself intervened telling Moses to take twelve staffs, one for each tribe, and deposit them overnight in the Tent of Meeting. The next morning, the staff bearing the name of Aaron and the tribe of Levi had sprouted, budded, blossomed and borne almonds. Only then did the rebellion end.
Each of us has our own personal relationship with our spirituality, our belief and G-d are set up to maximize that. We may not need a specific role or position to demonstrate it. This idea is captured by the following story involving two great leaders of the Mussar movement. Rav Naftali Amsterdam was talking to his Rebbe, Rav Yisroel Salanter, the movement’s founder. Rav Naftali said "If only I had the head of the Shaagas Aryeh [a great Lithuanian Rabbi of that time] the heart of the Yesod Veshoresh Ha'avodah [a great tzaddik and servant to Hashem] and the characteristic traits of the Rebbi [referring to Rav Yisroel himself], then I could be a good oved Hashem (server of Hashem)." Rav Yisroel responded, "Naftali, Naftali, with your head, with your heart, and with your characteristic traits you can be a true servant of God.” We are influenced those we have known and been inspired by yet we remain our own individual self. We should strive to reach a high spiritual goal each according to our unique nature.