Date and Place: 10 Sivan 5665, the holy city of Yafo

Recipient: R. Dr. Moshe Zeidel (a close disciple of Rav Kook, from their time in Boisk. Dr. Zeidel was a philologist and philosopher, who asked Rav Kook many philosophical questions.)

Summary of previous parts: There must be a limit to the propriety of free thought because it affects one’s actions and thus also his surroundings. The "location" of the "boundary" depends on the nature of different nations. For Israel, whose task it is to inform the world about Hashem, this requires stricter adherence to philosophical truths. Yet, at times, Hashem is not interested in us being able to carry out our task easily, and we are unable to keep discipline within the nation.

Body: This explains what I wrote [in the open letter]. Now we move on to deal with [how to handle an imperfect situation].
Even though it is fully forbidden and a bad disease to even be unsure or to think with doubts about matters that warrant full belief, we still find Chazal attaching a status of an apikorus (roughly, heretic) only to a denier, i.e., one who decides the opposite of the proper belief. It is only possible to find one in Israel to adopt the opposite of the true beliefs if he is a totally evil person and purposely lies. The greatest evil can only cause doubt for those who possess weak minds.
Therefore, one who is brazen enough to say that he clearly rejects a tenet must be a totally evil person. Then it is proper to rule upon him all of the explicit laws, and he cannot claim that his heart forced him into those decisions. If there were any honesty to the denial of proper belief in our generation, it would only cause one to raise doubts, and it would be easy to explain the answers. In contrast, heretics willfully claim to be definitely right, whereas even the weakest minds would only get to doubts, but they are involved in the evil of pursuing [a false agenda]. Therefore, he is subject to all of the laws, those administered by man and those administered by Hashem, according to the degree of the stumbling block [for others] that he caused. The details of these laws need to be presented at great length in many books.
It is clear that whoever understands how all heresy in relation to Israel is only a claim of a weak doubt, which comes about through lack of knowledge, lack of feeling, and lack of morality, would immediately become complete in true belief and fear of Hashem. The more one would connect himself to Torah scholars, who seek out Hashem in truth, the more he would elevate himself step by step and would be full of belief of the strength of knowledge and wisdom. "Any instrument that would be created to harm you will not succeed, and any tongue that would rise up against you in legal dispute will be vilified. This is the portion of the servants of Hashem and their righteousness from Me, said Hashem" (Yeshayahu 54:17).