What does the Catholic Church teach about Spiritism, especially the Kardecist Spiritualism Doctrine (covered in the link above)? According to the Catholic Church, it is wrong to try to communicate with the dead and to gain knowledge from spirits?
The Catechism of the Catholic Church has a paragraph specifically referenced as "Spiritism — forbidden" in its index, and which unequivocally and categorically condemns the practice of spiritism.
2117 All practices of magic or sorcery, by which one attempts to tame occult powers, so as to place them at one's service and have a supernatural power over others — even if this were for the sake of restoring their health — are gravely contrary to the virtue of religion. These practices are even more to be condemned when accompanied by the intention of harming someone, or when they have recourse to the intervention of demons. Wearing charms is also reprehensible. Spiritism often implies divination or magical practices; the Church for her part warns the faithful against it. Recourse to so-called traditional cures does not justify either the invocation of evil powers or the exploitation of another's credulity.