i
All the people are holy, and God is amongst them. And so everyone, and not only the priests, should be let to serve in God's Temple.
That is Korach's rallying-cry: through which he leads a rebellion against the whole concept of a priesthood.
God calls Korach's followers in this rebellion sinners.
ii
God
has recently told the people to take up their tribes' positions within
the camp—Judah at the front; Levi in the center; the priests at the
Tent of God; and so on—as the people travel together towards the Land.
Before, they had all dwelt together: a single group at the base of the Mountain, learning the Laws and learning what they will need to know when they enter the Land, like children at school.
Then, the people graduated into their specific roles: Judah at the front; Levi in the center; the priests at the Tent of God; and so on.
iii
But Korach said: all the people are holy. He wanted everyone to be priests, together. He did not want anyone to graduate into differentiated roles, into unique lives.
He hoped that the people would remain schoolchildren forever.
That was the basis of his rebellion. And that was his sin.
~~~~~