Idolatry originated with the Generation of Enosh: Shabbat 118b
Because the Jews Martyred themselves rather than commit idolatry, the prohibition has stayed strong: Shabbat 130a
Disgracing the Intermediate Days of holidays is like worshipping Idolatry: Pesachim 118a; Makkot 23a Arrogance is compared to idolatry, and to denial of Gd's existence: Sotah 4b Arrogance is like building an altar for idolatry: Sotah 4b
The gravity of the punishment for idolatry: Taanit 5a-b Gd always sees idolatry: Bava Metzia 59a
