Fundamental preconceptions are sacred to us. They form the basis of everything that we know and believe. They tell us how to be right, and who else is wrong. We immediately know false statements when they contradict our preconceptions and immediately know true statements when they follow from our preconceptions. Our entire perspective of reality and righteousness is based on its alignment with our fundamental preconceptions.
Thus, when you attempt to break the fundamental preconceptions of another, you are attempting to do no less than crush their entire conception of reality. This is no mere disagreement; it is a great cosmic event with the greatest of stakes hanging in the balance. To what extent one is prepared to engage in that conversation varies wildly from person to person.
If you succeed in breaking the fundamental preconceptions of another, and they were not ready for it, you have done nothing less than dropped them into the pits of hell. There is now no sensibility to the world for them, no comforting reason, all that should be is not. If they are ready, and you are speaking the truth, then it can be the beginning of their ascent to heaven.
None of this is to say that people should be left in their deep delusions, but it does deserve proper respect for what we are doing when we try to rouse people out of them.