Question: What does "church" mean?
Answer: The word church is from the Greek word ekklesia. Ekklesia is not a religious word as originally used among the Greeks. Ekklesia is a compound word meaning "ek, out of, and klesis, a calling" (W.E. Vine, vol. 1 pg. 83). The word is used in its basic, secular sense in Acts 19: 32, 39 - an assembly and, then, a lawful assembly.
The Holy Spirit spiritually used the word church. The first time ekklesia (church) is used in the spiritual sense is in Matthew 16:18, where Jesus promised to build His church (ekklesia). Applied spiritually, ekklesia suggests the called out of - that is, the saved who are called out of the word (John 17). "Church" (ekklesia) is used to denote all the saved without any particular geographic designation (Matt. 16:18), and of the saved in a particular geographic area (1 Cor. 1:2). "Church" used universally (all the saved) is always used in the singular. "Churches," plural, refers to a number of local churches, the saved in geographic areas. The Churches crafted by man, regardless of intention, are NOT the true Church. It is not hard to find over 2,000 different "churches" just in the United States. The ONLY church is the one started by Christ Jesus. Check (study) the Bible and one finds there is but ONE church. It is named and refered to in the Holy Bible as The Church of God!
Though Paul wrote, "... The churches of Christ salute you" (Rom. 16: 16). "Churches" is applied to the assembly of God's people (1 Cor. 14:19). "Church" denotes the saved who have banded together and have the full development as far as organization is concerned (Acts 14:23). The local church, when fully organized has elders (bishops) and deacons (Phil. 1:1; 1 Tim. 3:1-13). "Church" is also used of the banded together saved in the absence of the full organization (Acts 14:23). Those churches were ALL The Church of God.
How "church" is not used. Out of the 115 times "church" is used in the Greek New Testament, it never refers to the building in which the church meets. "Church" is also never used to denote denominations. Christ Jesus declared, "I will build My Church" (Matt. 16:18). He did not say "churches," "fellowships," "sects, "demoninations" or community of believers" (Pack, D.C., 2015). Denominations, as such, did not exist in the First Century, "church" is not applied to unauthorized religious groups such as the Nicolaitanes, etc. (Rev. 2:6, cf. vs. 1). As I have stated in other parts of this website...DO NOT simply take my word for it. Open your Bible(s) and prove this to yourself. Church, churches, religions, denominations, etc. were all huge stumbling blocks to my FULL understanding of what I was studying in the Bible.
The Church Which Christ Builds
As simple a task as it might appear to be, understanding what the Church is, one MUST have a sound doctrine upon the subject of "the Church." Be aware of the fact that "A mistake here may lead on to dangerous and soul-ruining errors" (Ryle, p.224). The true Church is the body of Christ Jesus. This is the holy Catholic and Apostolic Church - not to be confused with the Roman Catholic Church. It is Christ who calls the members of the Church in due time. They are "the called of Jesus Christ" (Ryle, p.224).
(Source: Chapter 13 in Holiness, Ryle, J.C.; www.ccel.org/ccel/ryle/holiness.html)