Our Gemara on Amud Beis brings a proof that one can eat from meat slaughtered by a Jewish transgressor with regard to idol worship. The proof comes from Yehoshaphat, king of Judea, who partook of the feast prepared by Achav, king of Israel, who was a transgressor with regard to idol worship.

Some ask, why not bring a proof from Yitschok who asked to eat from Esav’s hunting? After all, the Midrash states that Esav was an idolator already prior, at the time that Yaakov purchased the Birthright (see Rashi Bereishis 25:27.) The simplest answer is that Yitschok did not know that Esav went astray, as the plain reading of the verse states, (ibid, 28): “And Yitschok loved Esav because he fed him trappings.” The Midrashic explanation is that Esav trapped Yaakov and “fed” him lines of false piety (see Rashi ibid.)

If so, one might ask, but still we have a tradition that God does not allow the righteous to transgress eating non-kosher, even inadvertently (see Gittin 7a and Tosafos.) If so, how could God have allowed Yitschok to be in the dark about this? The elegant answer is that, after all, Yitschok never ended up eating from Esav’s hunting because Yaakov fed him first. (Though the simple reading of the text we quoted shows that Yitschok enjoyed food hunted by Esav, perhaps this was retrospective, from before Esav went bad.)

I will add a thought. Yitschok could see no wrong with his son, Esav. The Midrashic peshat is that Esav smooth-talked his father, and “fed him trappings.” But there is a question: Who was fooling whom? There is an adage, the best con men make the person think he is conning you. Yitschok’s refusal to see evil in Esav can be read as seeing his good qualities and strengths, such that he was a hunter and devoted to his father. This could have “fooled” and inspired Esav into being better than he was, because Yitschok could only see it as good. In the end it didn’t, and Esav made his choices. Even then, who was fooling whom? If Yitschok wanted to see Esav with a critical eye, he could have. The point might be that he was right for not. What Esav did with it, was his business.