What does Isaiah 8:19 mean?
Despite upcoming judgement, Isaiah has announced He will not be shaken from his faith in the Lord (Isaiah 8:17). He would continue to hope in God. The people of Judah, though, would not remain so faithful. Unsatisfied with the Lord's words through Isaiah, they would turn to other sources to attempt at getting information or help regarding their uncertain future.The Lord tells Isaiah how to respond when people suggest information from "mediums" and "necromancers." These would be people who try to communicate with the spirits, or the souls of the dead. Ancestor worship was a common practice in this time. Various rituals were used to keep the spirits of the ancestors content as well as to try to earn their favor and protection. Those who have rejected faith in the Lord may end up seeking help from other "sources." Apparently, some believed that the dead "spoke" through high-pitched chirps and hard-to-follow muttering, which is likely how the Spiritists spoke when trying to channel the dead.
The Lord asks the most obvious question: Why are His people bringing questions to the dead instead of to their Lord God? Israel's first king, Saul, did exactly this in desperate moment of uncertainty. Saul panicked and chose to visit the witch of Endor to seek answers from the prophet Samuel's spirit (1 Samuel 28). Although this may seem like an act of faith on Saul's part, the Lord did not approve of Saul's choice. The Lord allowed Saul to communicate with Samuel. The deceased prophet repeated his previous message, that the Lord's judgement was coming. It is important to note that this was not due to the witch of Endor's power but completely due to God allowing Samuel to speak to Saul (1 Samuel 28:12)