Ach you guys got it all wrong, in Mesachtos Kiddushin Daf Lamed Tes (I think) it says that Achar became an Apikores becuase he saw a boy doing two Mitzvos that the Torah promises a long life (Sheluach HaKan and Kibud Av) getting killed.
Another reason is that he saw the tongue of Chutzpas HaMaturginin (a big tzaddik)
getting dragged on mud by the Romans (when they murdered him). So Achar said “The tongue that says pearls of Torah gets dragged on the mud!” So he sinned.
Check it up I think I’m right.
Also arent we getting a bit off topic?