Rav Kook on Heresy
From David Guttman;
When one speculates about God without [secular] knowledge and without Torah, one develops in one’s mind a dark image, full of emptiness and confusion. When that person now turns to divine worship based on this previous empty concept, man slowly loses the splendor of his existence, because he becomes attached to empty and confused ideas. When this goes on for several generations, it is inevitable for Kefirah to show itself culturally[1] with the goal of eradicating the memory of God and all the trappings of God worship. But ultimately, what is it eradicating? It is eradicating nonsensical and hopeless ideas that truly interfere between man and the light of the true God. It is upon these destroyed ruins trampled by Kefirah, that God’s supreme wisdom builds its temple!
(Shemona Kevatzim volume 1, page 31).