Question: "Which church is the true church?"
Answer: Which church—that is, which denomination of Christianity—is the “true church”? Which church is the one that God loves and cherishes and died for? Which church is His bride? The answer is that no visible church or denomination is the true church, because the bride of Christ is not an institution, but is instead a spiritual entity made up of those who have by grace through faith been brought into a close, intimate relationship with the Lord Jesus Christ (Ephesians 2:8–9). Those people, no matter which building, denomination, or country they happen to be in, constitute the true church.
In the Bible, we see that the local (or visible) church is nothing more than a gathering of professing believers. In Paul’s letters, the word church is used in two different ways. There are many examples of the word church being used to simply refer to a group of professing believers who meet together on a regular basis (1 Corinthians 16:9; 2 Corinthians 8:1; 11:28). We see Paul’s concern, in his letters, for the individual churches in various cities along his missionary journey. But he also refers to a church that is invisible—a spiritual entity that has close fellowship with Christ, as close as a bride to her husband (Ephesians 5:25, 32), and of which He is the spiritual head (Colossians 1:18; Ephesians 3:21). This church is made up of an unnamed, unspecified group of individuals (Philippians 3:6; 1 Timothy 3:5) that have Christ in common.
The word church is a translation of the Greek word ekklesia, meaning “a called–out assembly.” The word describes a group of people who have been called out of the world and set apart for the Lord, and it is always used, in its singular form, to describe a universal group of people who know Christ. The word ekklesia, when pluralized, is used to describe groups of believers who meet together. Interestingly enough, the word church is never used in the Bible to describe a building or organization.
It is easy to get ensnared by the idea that a particular denomination within Christianity is “the true church,” but this view is a misunderstanding of Scripture. When choosing a church to attend, it is important to remember that a gathering of believers should be a place where those who belong to the true church (the spiritual entity) feel at home. That is to say, a good local church will uphold the Word of God, honoring it and preaching faithfully, proclaim the gospel steadfastly, and feed and tend the sheep. A church that teaches heresy or engages in sin will eventually be very low on (or entirely bereft of) those people that belong to the true church—the sheep who hear the voice of the Shepherd and follow Him (John 10:27).
Members of the true church always enjoy agreement in and fellowship around Jesus Christ, as He is plainly revealed in His Word. This is what is referred to as Christian unity. Another common mistake is to believe that Christian unity is just a matter of agreeing with one another. Simple agreement for the sake of agreement does not speak the truth in love or spur one another on to unity in Christ; rather, it encourages believers to refrain from speaking difficult truths. It sacrifices true understanding of God in favor of a false unity based on disingenuous love that is nothing more than selfish tolerance of sin in oneself and others.
The true church is the bride of Christ (Revelation 21:2, 9; 22:17) and the body of Christ (Ephesians 4:12; 1 Corinthians 12:27). It cannot be contained, walled in, or defined by anything other than its love for Christ and its dedication to Him. The true church is, as C. S. Lewis put it, “spread out through all time and space and rooted in eternity, terrible as an army with banners.”