Orthodoxy has built a system of reward and punishment hereafter, based, to a large extent, on the acceptance of certain creeds, dogmas and doctrines. Nearly every sect has taught in the past, and many still do today, that acceptance of their particular brand of teaching was the only passport to heaven. Obviously, the people who are really competent to tell you what happens in the life beyond this are not theologians, who can only speculate and theorise, but individuals who live there and speak from personal experience. Yes, Maurice Barbanel is biased, but he makes a good point. Religions deal in faith and belief .
Spiritualism claims to deal in fact.
Barbanell says we should listen to what people tell us who live in the Spirit world. The Spiritualist position is explained elsewhere in this site. Thus, mediums act as a sort of telephone. There are several key points here. Firstly, anyone can try to develop aptitudes and become a medium.