There was no mercy from God for this presumptuous sin. These people were warned. They were told explicitly that what they were doing was a sin, what would happen, and that God would not be with them. But they went anyway! They presumed to go up to the mountaintop.
So another thing about presumptuous sinis that it is continuing proudly in the face of advice (and warning) to the contrary. What we see here is that presumptuousness can be rash on the one hand and quite premeditated on the other. But the constant concept behind these things is pride, arrogance, defiance, self-importance, and self-reliance.
It is an ambitious "go get 'em" attitude—one is going to succeed in what you want to do, come hell or high water. No matter what happens, a person will to carry through on his plan—even if God Himself should say, "Don't do it!"
Richard T. Ritenbaugh