Moses interceded with the Almighty to save the nation from destruction. With the incident of Korach, there is again the issue of leadership, but this time it was an active participation to change the structure as the people had known it. Moses in this instance petitioned the Almighty to remove the enemies because they were overtly and purposely seeking to corrupt the nation for their own ends. One should note that the Almighty granted these two petitions by Moses. Parashat Korach shows the power of speech.
People can inflict great injury upon themselves or others via the spoken word.
Some believe that another lesson taught by our Torah reading is that God is just, and punishes or rewards measure for measure. Furthermore, some explain that today's Torah reading teaches that the world belongs only to God. A very important lesson that Parashat Korach teaches is that you know your real friends when you are in trouble. The 250 men who joined Korach were leaders of Israel, and were expected to be loyal to Moses. However, they betrayed him.