This week we read a double Torah portion, Behar-Bechukotai. In its commentary on the first of the two, the Zohar states that the Patriarchs—Abraham, Isaac, and Jacob—each rectified one part of Adam (Zohar III, 221b, Ra’aya Mehemna). Through the consumption of the Forbidden Fruit and the aftermath of that event, the Zohar states that Adam was, in effect, guilty of three cardinal sins.
In Jewish law, one is supposed to violate any mitzvah if they are threatened with death—except for three: idolatry, forbidden sexual relations (giluy ‘arayot), and murder (see Mishneh Torah, Yesodei HaTorah 5:2). When Adam and Eve consumed the Fruit, the sin was akin to idolatry: ignoring God’s command and taking the advice of the Serpent instead. Moreover, idol worship itself began in the generation of Enosh, Adam’s grandson (Genesis 4:26). Adam was alive and well at the time, and should have prevented this development. For these reasons, it is considered that Adam transgressed the sin of idolatry.