This week's parsha focuses on Korach's quarrel with Moshe Rabbeinu and his subsequent downfall. Rashi (Bamidbar 16, 1) asks the obvious question: what possessed Korach to argue with Moshe? He explains that Korach felt the position of nasi should have been his, and therefore he was jealous of his cousin Elitzafan ben Uziel who received the appointment. As the Mishna in Avos (4, 21) tells us, this jealousy literally "took him out of this world," and he was swallowed alive into the ground.
Rav Wolbe (Alei Shur vol. I pg. 102) elaborates on the above Mishna. He cites the Rambam who explains as follows: "The Mishna states that jealousy, desire, and love of honor take a person out of the world. The reason is because possessing these three middos, or even a single one of them, inevitably causes a person to forfeit his emunas haTorah." It is clear that the Rambam understood "the world" mentioned in the Mishna as a reference to a person's emunah. Why is it that specifically these three things cause a person to lose his emunah?
Emunas HaTorah is belief in the fact that spirituality is a reality. Ta'avah - physical desire, stands diametrically opposed to one's ability to connect to spirituality. As the Chovos Halevovos writes (Shaar Haprishus chap. 2), the purpose of the Torah is "to enable one's logic to reign over his desires." Hence, getting caught up in fulfilling physical desires detracts from one's ability to believe in spirituality as a reality.
Jealousy hinders a person's ability to perceive Divine Providence. If he would truly believe that everything Hashem does is calculated to the very last detail, there would be no room left for jealousy. How could one be jealous of what his friend has when he knows that Hashem explicitly decided that he doesn't need or deserve that specific thing?
Finally, he who runs after honor is clearly lacking in his belief that true reward and punishment are allocated only in the next world. One who is cognizant of this fact does not feel the need to seek honor, because he knows that his actions will be aptly rewarded in due time. Moreover, as Rabbeinu Yonah writes (Sefer Hayirah), the honor he receives might even detract from the reward he is meant to receive in the next world.
The Rambam tells us that a person's "world" is his emunah. In light of the above, a great way to work on emunah is by diminishing our pursuit of jealousy, desire or honor. This is easier said than done being that most things we do are somehow connected to some sort of self aggrandizement. Nevertheless, merely being aware of the detrimental effects of these middos is already a step in the right direction!