The Salem Witch Trials are a poor example of religious extremism. Salem village was rampant with prejudice and panic which caused chaos and confusion. The witch trials were conducted, not by churches or religious authorities, but by secular courts. At the time, churches of all kinds generally opposed the Salem Witch Trials.
The trials were a demonstration of how much damage can be done when we set aside the rule of jurisprudence and allow religious extremism and religious superstition, ignorance and intolerance can perpetuate within a society and cause mass hysteria, which led to the unnecessary murders that became routine events during the trials.