Someone asked me today regarding the famous statement of Rav Chaim - did he actually act on it? In other words did he examine witnesses at a chasana as to whether they had correct beliefs. Did he refuse to count an ignoramous in a minyan because of mistaken beliefs. I am aware that it is a machlokess - but l'maaseh - what did Rav Chaim do?
Rav Elchonon Wasserman (Explanations of Agados #2): The view of the Rambam is that a person who believes G‑d is physical is a heretic. The Raavad commented: “There are greater and better people than the Rambam who erred in this issue because of mistakenly accepting the literal meaning of verses and agada.” I heard in the name of Rav Chaim Brisker that the Rambam views that there is no such thing as inadvertent heresy. Irrespective of how a person arrives at a mistaken belief, the fact is that he believes something which is heretical. Furthermore, it is impossible to be a member of the Jewish people without proper faith. Rav Chaim used to say that “a nebach apikorus (mistaken heretic) is also a heretic.”