Speaking of the big three, In the recent torah reading, the three
thousand of the Eruv Rav (converts who left Egypt with the Jews) killed
after the Golden Calf had been quick to cast off the yolk of Heaven when
they thought Moshe erred on the 40 day duration on Sinai.
Based on sefer (the book) 'Divrei Yizchak II':
1) The Eruv Rav (not Israel) considered the Eigel (calf) a symbol of a
force of nature independent of Hashem.
2)They reverted to having relations with other than their husbands,
- Just as we Jews have a commandment for the wife to be faithful solely to
her husband so are we as a nation commanded to be faithful solely to Hashem.
3) They murdered Moshe's nephew Hur.