This week I was challenged to explore the question, "what is the Church?". So I have, and I thought I would share here, for the record, what I found.
The word “church” comes from the Greek word ekklesia which is defined as “an assembly” or “called-out ones.” Nowhere in the Bible is the place where Christians meet referred to as a "church." This word appears around 75 times in the English Bibles, depending on the translation (around 110 times if you include the plural). Never does ekklesia refer to a building in which people gathered, for worship or for any other purpose. This tells us that the Church is not a place we go, but rather a group of specific people. In Romans 16:5, Paul says to "greet the church that is in their house". He refers to the people meeting in the house, not the building housing the people. I don't think there would be any intelligent argument to this fact in most religious circles today.
Now, to be more specific: this people are those who have been filled with the Holy Spirit upon repentance from their sin and conversion to the lordship of Jesus in their lives. This people called the "Church" in scripture are the body of Christ, of which He is the head. Looking at Ephesions 1:22-23, Paul says, "And God placed all things under His (Jesus) feet and appointed Him to be head over everything for the Church, which is His body, the fullness of Him who fills everything in every way." The New Testament Church is a body of believers who have been called out from the world by God to live as His people under the authority of Jesus Christ. I find in scripture that there are two aspects of the Church manifest in the world - the universal Church and the local church. Let me look closer at the two.
The universal Church would be all those who have this personal relationship (not a personal knowledge of) with Jesus Christ. 1 Corinthians 12:13 makes this clear when Paul tells us, "For we were all baptized by one Spirit into one body — whether Jews or Greeks, whether slaves or free — and we were all made to drink of one Spirit." Everyone who calls upon Jesus as Lord and has put their faith in Him and His sacrifice on Calvary to pay the price for their sin is a part, or a member, of the body of Christ and has received the gift of the indwelling of the Holy Spirit as evidence of this decision.
The local Church, in mathmatical terms, is a "subset" of the universal Church. In Galations 1:1-2, Paul writes, "Paul, an apostle — not from men or by man, but by Jesus Christ and God the Father who raised Him from the dead — and all the brothers who are with me: To the churches of Galatia..." Paul was not addressing a group of denominations, ie, the first Baptist Church of Galatia, the Methodist church, the Catholic church, First Assembly of God church, etc... He was writing to the smaller, local bodies of believers (as mentioned earlier in Romans 16:5) who met together in various houses. How do we know this? History tells us throughout the Roman persecution of Christianity that for a local body to own property would have been a death sentence on all attending there. Only after the emporer Constantine declared Chritianity "legal" and ended persecution (from the Romans, anyway) would it have been possible. The first record of a dedicated church building dates back to the mid third-century. Galations was written around 49 A.D. The local Church is the place where the members of the universal Church should fully apply the “body” principles of 1 Corinthians 12: encouraging, teaching and building one another up in the knowledge and grace of the Lord Jesus Christ. A person becomes "a member" of the local and universal Church simply by exercising faith in Jesus Christ as Lord and Savior.
Now, what is the purpose of the Church? Again, I find a two-fold purpose: the first and primary would be to bring glory to it's Head, Jesus Christ. How do we do this? By fulfilling the second purpose, which is fulfilling God's plan for the earth. Again, I find a two-fold purpose, the first being to edify fellow members of the Church body and the second to be the evangelism of, or sharing the Gospel with non-believers for the purpose of bringing them to making a salvation decision. Acts chapter 2 gives a great description of how this looks.
"Now all the believers were together and had everything in common. So they sold their possessions and property and distributed the proceeds to all, as anyone had a need. And every day they devoted themselves [to meeting] together in the temple complex, and broke bread from house to house. They ate their food with gladness and simplicity of heart, praising God and having favor with all the people. And every day the Lord added to them those who were being saved." (44-47)
By building up each other, rather than just making sure selfish wants and needs were met, the lost community took notice of something amazingly different about this particular group of people. This opened the door to share the Gospel and as a result, people came to give their lives to Christ on a daily basis - which brings honor and glory to God.
This is what I find in scripture as to what the Church is.