The Greek word translated church is "ekklesia" which means an assembly, then a religious gathering/group and then the gathered body of Christ. In Matthew 16:18, Jesus spoke of the church as something which He was to build in the world: "...I will build my church...." The context has Jesus saying He would build His Church on a rock, "Petros" meaning a massive rock as compared to Peter -- "Petra" meaning a small detachment of a great rock. Jesus affirms; He will build "oikodomeso" which is future tense. This building was to be done ahead of that moment of time. Jesus uses the word church one more time in the Gospels: Matthew 18:17 "...tell (it) unto the Church; but if he neglect to hear the Church...." The word for church, "ekklesia", is frequently used, beginning in Acts, then in the other epistles of the New Testament. Acts 2:4 reads: "...the Lord added to the Church daily...."

Here, the church has become a living organism of Christian believers; a growing organism, as new converts were saved and received into the body of believers. These new converts were recognized as fellow believers in the Savior and Lord Jesus Christ by water baptism. In this way, each believer in Jesus Christ, as his/her Savior, in repentance of sin, became part of the church of local believers. In turn, they were nurtured in Christ to maturity, for the service of Christ; being part of the growing spiritual organism, the Church.

The expansion of the Church was ongoing from place to place as evangelists preached the Word and believers were added to the Church of God/Christ. So, there would be a building of local churches everywhere to the ends of the earth.

We find instructions for the internal workings of the local churches in Ist Corinthians 12:28f. This includes: individual gifts, ministries, workings, operations as given and administered by the Holy Spirit. Note verses 27 and 28 in which are given individual members of the body for leadership and orderly workings as a unified whole: "God hath set some in the Church (singular) apostles, prophets, teachers...." First, the apostles are major building stones or rocks used of God. These would be the apostles whom Jesus called or calls. "Apostolos" means a messenger who is commissioned as an agent of the Lord, to faithfully deliver the message/gospel of Christ. There could be no expansion of the Church body of Christ without the Gospel of Christ: "... then faith is from hearing and hearing through a word of Christ:" Romans 10:17 (literal translation of the Greek text).

The work of building up of the body of Christ, the Church, is continuing and will continue until Christ, through the Holy Spirit, is finished. Then, the full body of Christ will be gathered from heaven and earth together as the Bride of Christ for a marriage of eternal reigning in the New Jerusalem and the new heaven and earth. (Revelation Chapter 21.)