This verse is Paul's summary of the church. He writes dogmatically, proclaiming a truth which was always God's idea. His church (the 'called out' people) is the body of Christ in the world. There are many parts (1 Corinthians 12:12), but the parts do not make the character of the whole, because it is divinely shaped to be like the Lord Jesus Christ. The church is His intentionally-built Body: not the amalgamation of the spiritual experiences of many individuals, but divinely shaped to be like Jesus.
 
The breadth of the parts of His church is expressed in Revelation 5:9. Speaking about Jesus, the leaders proclaimed, "…you were slain, and with your blood you purchased for God persons from every tribe and language and people and nation." There is no country, ethnic background, language or cultural group which will not be represented in heaven. Some of them are already in His heavenly presence; some are now members of churches throughout the world. Some worship and preach in joy and freedom; some praise joyfully but know persecution is not far away. All these people are our brothers and sisters, seeking to obey God's Word and to be led by God's Spirit.
 
Over the centuries, the church has often been under attack but it is kept by the power of God because it bears the likeness of the Son of God (1 Peter 1:5). Its unity is not through the determination of individuals to agree a plan, but because of God's determination to establish an eternal kingdom which demonstrates the nature of Jesus (Matthew 16:18). People are only in Christ's church because God's love has drawn them, His blood has ransomed them and His Spirit has led them to repentance and given them eternal life. The church belongs to Christ, expresses Christ and gives glory to Christ.
 
If you have come to Jesus in repentance and faith, you belong to His earth-wide, heaven-high church. He has the right to give you abilities to serve Him, and to locate you wherever He chooses to fulfil whatever function He has determined. In that there is great security, but also great challenge as you work alongside other sinful people who have been saved by His grace. Although you are only a part, being a part of Christ you lack nothing; and He can do anything He chooses with and through you. It is a wonderful privilege to be a part of His church.