Numbers 13:28—14:4 speaks of the unbelief of God's chosen and redeemed people. This took place at Kadesh-barnea, after the spies had come back from spying out the good land. With the exception of Caleb and Joshua, the spies brought back an evil report, saying, "The land, through which we have gone to spy out, is a land that devours its inhabitants; and all the people that we saw in it are men of great size. And there we saw the Nephilim (the sons of Anak are from the Nephilim); and we were in our own sight like grasshoppers, and so we were in their sight (13:32-33). When the people heard this, they wept. Their weeping was not only a matter of unbelief but also of rebellion.
The unbelief of the people provoked God's anger toward them (14:11-12).
This unbelief also caused them to forfeit the right to enter the God-promised good land (vv. 22-23).
God punished the people by causing them to wander in the wilderness and to be consumed there (vv. 32-35). God said to them, "Your little ones, who you said would become a prey, I will bring in, and they shall know the land which you have rejected. But as for you, your carcasses shall fall in this wilderness" (vv. 31-32).
In Numbers 16:1-12 we have the record of a corporate rebellion, the rebellion of Korah, Dathan, Abiram, and two hundred fifty leaders. Korah was a Levite, and Dathan and Abiram were leaders among the people. They convinced two hundred fifty of the leaders to join in a conspiracy to rebel.
Korah, Dathan, Abiram, and two hundred fifty leaders of the assembly "gathered themselves together against Moses and against Aaron, and said to them, You have gone too far! For all the assembly is holy, every one of them, and Jehovah is among them. Why then do you exalt yourselves above the congregation of Jehovah?" (16:3). This indicates that these rebellious ones were jealous of the high position of Moses and Aaron. This matter of jealousy concerning position and leadership has always been a problem among God's people. Often, those who are jealous in this way have ambition but do not have the capacity to match their ambition. Throughout the history of God's people, rebellion has been caused by the combination of ambition and the lack of capacity. This was the situation in Numbers 16. Korah, Dathan, and Abiram were ambitious, but they did not have the capacity which Moses and Aaron had.
Korah was not satisfied to be a leader in the Levitical service, which was secondary to the priesthood, and Dathan and Abiram were not satisfied to be leaders in the assembly of God's people (vv. 8-11). They all wanted a higher position, but according to God's sovereignty, they did not have the capacity for such a position.