How do we know that Christ's fire is meant to destroy false doctrine?

The fire that Christ speaks of serves to highlight the difference between truth and error. In 1 Kings 18, the fire that consumes the sacrifice at Elijah's call demonstrates God’s power against false gods. This theme carries into the New Testament, where Jesus indicates that His coming will cause division—clearly showing the discord sown by the truth of the gospel in a world filled with error. The ultimate purpose of this fire is to reveal who God truly is and to purify His people by burning away corruption and false teachings.