How do we know the union of Christ and the Church is eternal?

The Scriptures portray the relationship between Christ and His Church as a sacred marriage, which reflects eternity. In Ephesians 5:31-32, Paul refers to the union of husband and wife as a mystery that reveals Christ's relationship with the Church. This union signifies that believers are joined to Christ in an inseparable way, with Christ as the head and the Church as His body. Such a relationship is established by God's eternal purpose, emphasizing that once united with Christ, believers are forever His, illustrating the unbreakable nature of this divine connection.