Idolatry Wisdom and Prophesy

 Rav Tzadok (Poked Ikkarim page 51)  When the Anshei Kenesses Hagadolah nullified the lust for idolatry it also ceased for the non-Jews. Thus our Sages stated that non Jews outside of Israel were not actual idolators but were simply keeping the customs of their ancestors and they also lost understanding and their wisdom was corrupted which was dependent on their desire and attatchment to idolatry.  Similarly prophesy diminished. Correspondingly the Oral Torah developed and grew during the Greek rule.