What does the Bible say about separation from the world?

In Nehemiah 3:8, we see the importance of fortifying Jerusalem with broad walls, symbolizing the necessary separation of God's people from the ways of the world. This biblical principle teaches that the church must maintain its distinctiveness through active nonconformity to worldly customs and spirit. The rise of laxity and the blending of church and world threaten the sanctity of God's people, leading to spiritual decay. Such amalgamation is warned against, as it introduces enmity against God, thus endangering the integrity of the church and its mission. It is crucial, then, for Christians to uphold the 'broad wall' of separation, ensuring that their walk is reflective of their calling as children of God.