The word ‘church’ comes from the Greek word ekklēsia, which means, ‘called out’ or ‘gathered people’, or ‘an assembly’.
The church is an assembly or gathering of a group of believers who put their trust in the finished work of Jesus Christ on the cross, who believe that Jesus is the only Lord and he is the only way to salvation, who believe that they cannot do anything to save themselves, who believe that Jesus has done everything for them to enable them to be in a relationship with the One True God. Not only do they believe this in their hearts, but they have also confessed it with their mouths and have boldly proclaimed their faith before the gathering of other believers when they were baptized into the body of Christ (Heb. 12:23; Col. 1:18; Eph. 1:10, 22–23, 5:23,27,32 1 Cor. 1:2; Acts 11:26; Rom. 1:7; Eph. 1:20–22).
So then to summarize: A church is a group of baptized believers who have covenanted together under the Lordship of Christ Jesus to regularly fellowship with one another and to help one another in their Christian faith and life.
What Is Not A Church?
Just a building
I think most people intuitively think of a church as a place where Christians gather together to meet and worship. Church for many is a religious building, a sacred place, a holy sanctuary. While it is common to use the word ‘church’ to denote a place of meeting i.e., a building, according to the Bible, the church is not a building but a group of people (Rom. 16:5).
Just a gathering
The church is not a group of people that merely meets together on a regular basis only to socialize, to have a sense of belongingness, to have a ‘feel-good’ time together or even have a religious experience together. A church is indeed a gathering, but it is a gathering of people brought together by the gospel of Jesus Christ for the worship of God (Acts 2:42).
Just a meeting of activists
Some people might be tempted to think of a church as a group of people that are very active in their communities for social, religious or political causes. You may have come across the wrong assertion that the church is the only institution that primarily exists for its non-members. However, a church is not a group of social or religious activists advocating for certain causes. Instead, it is a group of forgiven sinners who are seeking to help each other to grow in their Christ-likeness (1 Thess. 5:11; Heb. 10:24,25).
Just a group of people from a similar background
A church is also not a homogenous unit that is made of people of a similar kind, background, education, caste or culture who meet together because they will look out for one another because they are of the same kind. The Bible teaches that the church is a group of diverse believers whose central commonality is that they have been bought by Jesus’ blood (1 Cor. 12:13).
So, What Is A True Church?
Ever since the Reformation in the time of Martin Luther, the Protestant Church has sought 3 marks—the preaching of the Word, participation in the ordinances (baptism & the Lord’s supper), and the practice of church discipline—in a church to ascertain if it is a true church or not (Matt. 28:19–20; 1 Cor. 11:26; Matt. 18:17–18; 1 Cor. 5:4–5,13; 2 Cor. 2:6–8).
The Belgic confession (1561) says,
The true church can be recognized if it has the following marks: The church engages in the pure preaching of the gospel; it makes use of the pure administration of the sacraments as Christ instituted them; it practises church discipline for correcting faults. In short, it governs itself according to the pure Word of God, rejecting all things contrary to it and holding Jesus Christ as the only Head. By these marks one can be assured of recognizing the true church– and no one ought to be separated from it.
Note: None of the material is original to the author!