We examine Deuteronomy 13 and God’s instructions to ancient Israel regarding false prophets, family members, and entire cities that would entice his people into idolatry and covenant treason. This passage forces us to grapple with the seriousness of sin, the supremacy of loyalty to God above all other relationships, and the biblical principle of purging evil from the midst of God’s people. This sermon considers applications for the church and state today, while seeing how this same law ultimately points us to Jesus Christ. This sermon reminds us that God’s righteous law is good, that sin brings devastating consequences, and that true flourishing comes only through wholehearted devotion to the Lord, purging the evil from our midst.