The unity of believers is essential to God's plan in building one Church made up of all peoples who put their faith and trust in Jesus Christ. The Church is referred here to God's house, not a building of brick and cement, but a spiritual household of all Christians joined as a living organism. Christ, being the Cornerstone of the structure, sets the standard by which the building is erected. God Himself is the Architect and Creator of this "structure". Note also that the foundation is the preaching and teaching of God's ministers, both the apostles and the prophets. God gave them the privilege of presenting the facts of Christ and His finished work at Calvary. This building rests on rock-solid Truth and as Jesus put it, "The gates of hell will not prevail against it!" Matthew 16:18 KJV.