Isaiah contrasted his message with the advice of ungodly people around him. His message brought light and truth. The message of spiritists led to darkness and death.
Mediums tried to discover the future through divination (seeking hidden knowledge through rituals). Some claimed to speak with the dead (see Isaiah 19:3). However, God had forbidden these practices because they were empty and harmful (Isaiah 47:9; Deuteronomy 18:9–11).