Shavua Tov. The three biggest sins in the Torah were the selling of Yosef as a slave, the sin of the spies, and חטא העגל, the sin of the Golden Calf.
Rashi explains that there were three groups who sinned with the Golden Calf. Those who were warned and had witnesses, were punished with death by the sword. Those who had witnesses but no warning, died in a מגפה, a plague. And those who had no warning and no witnesses, had to drink the water that had the melted calf in it. They drank the water and if guilty, their stomachs exploded like the סוטה.
The Kabbalists say that this sin was so grievous that death returned to עם ישראל. The Jewish people on הר סיני reached the status of Adam and Eve before their sin, and at that time, as well, there would not have been death to humanity.
When Mashiach comes, we will once again return to that level once again. May that day come speedily.