Josh31, I agree with that, that we are defined primarily through our actions (maasim tovim) not what goes on in our minds.
I have a chiddush in the definition of an apikorus, which I see justification in the language of the Rambam in Hilchos AZ (2:5). He says apikorsim are those who stray after the thoughts of their hearts in the foolish matters we discussed (earier in chapter) until they end up violating actual prohibitions of the Torah lhachis, with a brazen soul, in a strong hand, and they say there is no sin in this. Later he says the machshavah of an apikorus is for avoda zara.
In other words, the Rambam seems to be saying that an apikorus invents his philosophy to be porek ol, and to rationalize his desire to violate the Torah which he then proceeds to do with a strong hand. My understanding of this is that a tnai in being an apikorus is actually carrying out the throwing off the yoke of Torah. The things he says or claims to believe are only to enable his real intentions of becoming hefker with no rules.
However, one who sincerely and fully keeps all the mitzvos, cannot be an apikorus. A yid is judged by his actions. One who acts like an ehrlicher yid is an ehrlicher yid. If one has trouble believing in something, but nevertheless says, although I can’t understand X, Y or Z which we are supposed to believe, but I fully intend to keep all the mitzvos which Chazal have taught us, that is not an apikorus.
Note similarly in the story of the Gerim who came to Hillel one said I believe in Torah Sebichsav, but not in Torah Shebal Peh. Hillel converted him anyway. Rashi says, shelo haya kofer, rak shelo hayah maamin, and Hillel was confident he would convince him of the authenticity of Torah Shebal Peh.
Rashi seems to be saying that not believing is not at all the same as denying something. One can be a Jew with sincere questions, as long as one does not use the questions to throw away the Torah or its Mitzvos.
Therefore, to call a sincere, learned, baal midos and prince of a man like Rav Kook an apikorus is beyond preposterous. He was one who never said a bad word about anybody and always saw the best in everybody, and tried to develop a warm relationship with even the most distant Jew. Reb Aryeh Levine followed in this derech, and was the Baal Tefila on the Yomim Noraim in Rav Kook’s yeshiva Merkaz Harav for many years.
Beautiful words from Rav Kook (lose something in translation):
The pure righteous do not complain about evil, rather they increase tzedek.
The pure righteous do not complain about heresy, rather they increase emuna.
The pure righteous do not complain about ignorance, rather they increase chochma.
Arpilei Tohar p. 39