Why is the punishment for unwillingness to enter the Land greater than the sin with the golden calf? Why is the punishment for that is greater than idol-worship?
ב"ה Shalom Based on the premise of my previous answer in regard to the golden calf, we can see things with a clearer perspective. That is to say, with all the severity of the sin of Bnei Yisrael, it was not an abandonment of G-d and actually believing in idols. (In regard to the majority) It was a misguided act in which they thought they can serve G-d , by praying to a tangible object. However, in the sin of the "Meraglim", those who did not want to enter Eretz Yisrael , in many respects their act was a lot worse. According to the Ramban on the Torah, they showed they were ungrateful to Hashem who promised them the Land.) Bamidbar 14:17) According to the Malbim ,the Meraglim were declaring that Hashem hates them. (Malbim Devarim 1: 32-33) and Hashem also wanted to make it clear to them that it was the fault of Bnei Yisrael which delayed their entrance to Eretz Yisrael. All the best