These days you hear differing opinions about the church, says Rev. Simon de Marie.[i] For example, it is said that you have to feel at home in the church; that with so much division among churches that call themselves reformed, it’s best to choose one in which you feel comfortable. Maybe a church that is not too small or too conservative. Or one that is conveniently close by. Or a church that your grandparents and parents were or are also members of.
Reformed people are quick to admit that the church must be a true church. But then come the rhetorical questions: Who determines that a church is true? All those different Reformed or Presbyterian churches, don’t they all serve the same God and the same Christ? As long as they do not permit Scripture criticism, then surely it’s okay?
And as for the Belgic Confession of Faith where we confess that you must be a member of the true church—doesn’t that term come from the time of the Great Reformation? At that time it was clear that the Roman Catholic Church was the false and the Reformed was the true church. Back then you didn’t have all those divisions that there are now. How can you still apply that to our time?
Furthermore, if you say that your church is the true church, isn’t that being rather arrogant? Aren’t you then writing off all those others? And if you talk about church unity, can you not, as members of different churches, at least conclude that you are one in Christ? Sure, there are all those different views, but in a way isn’t that a good thing?
Moreover, are there not many things different churches can do together, such as sharing things for mutual encouragement at an interdenominational conference? Or pulpit exchange or joint evangelism and/or a joint pastoral training? And isn’t this the way to show the unity in Christ?
This way, it is added, you can still accommodate all those divisions. Maybe with the thought that it’s a shame that you’re not completely one but, hey, that’s just the way it is. Be happy with what you still share together. That also makes it easy to change church federations, for example when you move somewhere else.
It is suchlike notions that one hears, says Rev. de Marie. However, the question is, is this the way God wants it? Is this the way Christ wants to see his church? Or is this merely human reasoning?
Christ and His church
Let us therefore first examine what Scripture and confession say about this, adds Rev. de Marie. For we may find something acceptable to ourselves, but we must ask ourselves: how does the Lord see it? He often asks of us things that go against our feelings and desires. And besides that, with Him things are possible that we do not think possible.
We first establish, says Rev. de Marie, that the Church of the Lord Jesus Christ is His work. He gathers a church, He does it, and He does it for Himself. He does this through His Spirit and Word in unity of the true faith. That’s how we confess that in Lord’s Day 21 of the Heidelberg Catechism.
And Christ’s gathering work in the unity of the true faith, is a unity in truth. That is the definition of “catholicity” in a nutshell, says Rev. de Marie. It is then important what truth is and what that unity entails. That means that all the emphasis cannot be on unity, as is done in the false ecumenism, such as the World Council of Churches. Truth is critically important.
Yet, adds Rev. de Marie, it is not only truth. For example, there might be a church which holds fast the truth but then, when it becomes aware of a federation of true churches, refuses to join it. That would make such an independent church schismatic. Or supposing there is a local church which has the marks of the true church but then remains in a federation which tolerates false teachings or practices. That would not be right either. Such a true local church is obligated to leave the false federation and join a true church federation.
Catholicity
We must emphasise that catholicity is both: unity and truth. Literally, says Rev. de Marie, catholic (“kata holos”) means: according to the full. According to the full number of all places and times and according to the full truth.
A church that is truly catholic also continually reforms itself in accordance with the truth of God’s Word. Again and again, the truth will have to be defended against heresy. Sometimes, e.g. if false doctrine is maintained despite objections, this even requires a church liberation. But that same, now liberated, church will also continue to look for other churches where the truth of God’s Word is also maintained.
Whilst truth of God’s Word comes first, unity in that truth is inextricably part of that, says Rev. de Marie; it shows that the church-gathering work of Christ is dynamic.
“Catholicity thus assumes faithfulness to the commission of Christ. He, as the sole Head of His church, demands that we continue to hold on to the truth of God’s Word and from there to continue to look where other true believers are. For both truth and unity, Christ gives His Spirit and Word.
It is Christ who calls us to his house. And we must obey that calling, by gathering where he calls. That is not a matter of ‘feeling at home’, but of serving and honouring Christ in a way that is pleasing to Him. Think of Heb. 12:22-29. And we do this together with all others who come our way through the call of Christ.”
One Shepherd, one flock
Hence true catholicity means being united in the truth. Admittedly, achieving unity in the truth in practice can feel fragile. Attempts to draw closer to other churches may quickly stumble over differences of opinion. That could lead people to ask: is deep, lasting unity even realistic?
Rev. de Marie’s answer is to return to one of the key passages behind Lord’s Day 21, to John 10. There Jesus reveals Himself as the good—indeed, the excellent—Shepherd. He knows His sheep, loves them, feeds them and protects them. His sheep recognise His voice and follow Him. Others—hired hands, false shepherds—do not care for the flock and do not follow Christ.
But Jesus also teaches that the one Shepherd desires one flock. First He gathers His sheep from Israel, God’s covenant people. Then He calls sheep from outside—Gentiles who hear His voice and follow Him. Christ does not form two flocks. He gathers all believers into one (John 10:16). Before Pentecost: one Shepherd, one flock. After Pentecost: still one Shepherd, one flock, because He gave His life for all who hear His voice and brings them into His one House (Eph. 2:14–16).
Christ’s prayer for perfect unity
Rev. de Marie next turns to Jesus’ High Priestly Prayer in John 17, prayed on the eve of His crucifixion. Here we see how profound this unity is meant to be.
We notice that Jesus first prays for the glorification of His Father, who will be honoured through Christ’s finished work and through the redemption of His people. He also prays for His own glorification and for the glorification of all who believe in Him.
Then He commends His disciples to the Father. Soon they will be apostles, left in a hostile world under the sway of the Evil One. Jesus asks the Father to preserve them and to anchor them in the truth of the Gospel.
From verse 21 onward, Jesus prays that this truth will bind His people together in faith. And He prays for a remarkable unity—not merely agreement in doctrine, but a unity modelled on the relationship between the Father and the Son.
This prayer extends beyond the apostles. Jesus prays for all who will believe through the Word—for the church across the world and across the centuries: “that they all may be one, as You, Father, are in Me and I in You… that they may be perfectly one.”
The unity Jesus desires, adds Rev. de Marie, is not unity on paper, nor unity expressed by occasional interdenominational gatherings. He prays for perfect unity—a unity in which the glory of Christ is visible through His Spirit.
Rev. de Marie explains how the apostle Paul also emphasises this perfect unity. In Romans 12 he speaks of one body with many members and many gifts. In 1 Corinthians 12 he expands the image: one body in which the one Spirit works through diverse gifts. In Ephesians 4 he again presents the church as the one body of Christ: one body, one Spirit, one faith, one baptism, one God and Father of all.
One body
From Christ the Head, the whole body is joined and held together. As each part does its work, the body grows in love and in truth—growing together toward Christ, the Head.
This unity is not confined to a single congregation, says Rev. de Marie. It extends between congregations, within federations, and among sister churches. In the apostolic era, this unity was nurtured through mutual concern, shared labour, and joint decision‑making. Timothy travelled between congregations; financial needs were shared; and the council of Acts 15 established guidelines for Jewish and Gentile believers—all for the sake of unity in the truth.
The Shepherd still walks among His flock
All true unity flows from Jesus Christ, the one Shepherd and the one Head. The unity we share with Him must continue in His body: in local congregations, in federations, and in worldwide sister‑church relationships.
This is the vision, says Rev. de Marie, of Revelation 1, where John sees Christ walking among the seven lampstands—the churches—His church in all places and times. He still walks among His flock. And where the Shepherd is present, His people are called to be one.
(to be continued)
[i] Rev. S de Marie is emeritus minister of what is now the “Reformed Churches”, a unity of what was formerly DGK (De Gereformeerde Kerken), of members who broke away from the GKv in 2003, and the GKN (Gereformeerde Kerken Nederland), whose members left the GKv in 2009. Rev. de Marie was of the DGK. The above article is condensed from the first two of four articles Rev. de Marie recently published with the same title on the website Bouwen en Bewaren – Dagboek en artikelen over geloof en kerk.