The following example made it clear to me how hard it is to convince people that spirits and angels exist, let alone that anyone can talk to them. There was a group of spirits I had known when they lived in the body who had been among the better-educated. (I have spoken with almost all those I had known during their physical lives—with some for several weeks and with some for a year—exactly as though they were living in their bodies.) They were once led into the same patterns of thought they had had when they lived in the world—an easy change to accomplish in the other life. The question was then suggested to them, “Do you believe anyone can talk to spirits?” “You would have to be deluded to believe such a thing,” they said then, in that condition, and doggedly continued to assert their opinion.
The experience showed how difficult it is to convince anyone that any speech between people and spirits is possible. The reason for the difficulty is that people do not believe in the existence of spirits, let alone in their own future arrival among spirits after death. This disbelief afterward shocked even the spirits themselves. Yet they were some of the better-educated and had often spoken publicly about the next life, and about heaven and angels. One would have assumed that the idea was very familiar to them as a simple fact, especially from the Word, where it comes up frequently.
from Secrets of Heaven, Volume 2, Section 1636