The Word of God is severely contrary to the practice of spiritism: consulting spirits, the souls of the dead, black magic, witchcraft and miracles (to see Exodus 7:11,22; 8:7,19; 9:11; 22:18; Leviticus 19:31; Deuteronomy 8:10 ,11,14; II Kings 17:17; 23:24; Isaiah 8:19,20; 47:9; Jeremiah 27:9 ,10; Ezekiel 13:23; 21:21; Daniel 2:2; 4:7; 5:7 ,8; Micah 5:12; Zechariah 10:2; Malachi 3:5; Acts 8:11; 13:6; 16:16; Galatians 5:19 ,20; 2 Thessalonians 2:9; Revelation 13:13; 16:14; 18:23; 19:20; 21:8).
The Law given through Moses condemns to death spiritistic mediums and the Bible warns us that in the last days some will apostatize of their faith, by obeying deceiving spirits and demons' teachings (Leviticus 20:6 ,27, 1 Timothy 4:1-2).
Its origin is as old as the Bible: it was already practiced in Egypt when Moses went to obtain permission from Pharaoh to remove the people of Israel (Exodus 7:11). Although they like to say they are Christian, deceiving many, in reality they deny the whole foundation of the Christian faith.
They don't meet around a common doctrinal base, or within a human leadership: the most outstanding of their writers write books intended for local leaders. Their beliefs have a common philosophical base, which can be summarized as follows:
On that base, their theories multiply and diverge in time and space, extending from philosophical and transcendental "high spiritism", like metaphysics and parapsychology, to which many intellectuals and people in high circles adhere, to "low spiritism" which involves tribal mysticism such as voodoo and macumba, and primitive religions in all continents. Buddhism has the same base.
Their sessions and experiences with communication with spirits allow for countless frauds of all types, by magic, individual and collective hypnotism and telepathy.
The consequences are fatal: as to the body, insanity, moral decadence and even death; in the spiritual realm, they will perish eternally.