The Nicene Creed confesses ‘one church’ (unam ecclesiam), meaning the church is built upon one rock, one Messiah, one confession. The Westminster Confession adds that the church’s unity lies in Jesus Christ: ‘The catholic or universal church, which is invisible, consists of the whole number of the elect, that have been, are, or shall be gathered into one, under Christ the Head thereof; and is the spouse, the body, the fulness of Him that filleth all in all’ (Chapter 25.1).
That the church is Christ’s body, and he its head (Colossians 1:18) implies that Christ and the church are complementary, since a body and a head cannot exist without each other.
Wilhelmus à Brakel expressed this truth by saying that the church and Christ are each other’s property. Their union is affirmed by the gift of Christ to the church; Christ’s purchase of and victory for the church; the indwelling of Christ’s Spirit within the church; and the church’s surrender by faith and love to Christ.
Christ’s fulness
To think of Christ without the church is to sever what God has joined in holy union. The church is organically related to Christ; she is rooted and built up in Christ (Colossians 2:7), is clothed with Christ (Romans 13:14), and cannot live without Christ (Philippians 1:21).
‘The church is in Christ as Eve was in Adam’, wrote Richard Hooker. The church is Christ’s fulness because the plenitude of his grace is poured out upon her (John 1:16; Colossians 2:9-10).
The church, Christ’s mystical body, ‘is like a vessel into which the fulness of Christ is poured’, wrote L. S. Thornton; ‘He fills it with himself’. Christ’s attributes – truth, power, mercy, love, patience, goodness, righteousness, wisdom – are both the embodiment of the church’s virtue and her resources.
Members one of another
All the members of Christ’s body are united to one another because of their common Head (1 Corinthians 12). All who confess Christ as their exclusive Saviour are ‘joined and united with heart and will, by the power of faith, in one and the same Spirit’, says the Belgic Confession in Article 27. They are united as members of the household of God, the community of Christ, and the fellowship of the Spirit.
There is one gospel (Acts 4:12), one revelation (1 Corinthians 2:6-10), one baptism (Ephesians 4:5), and one Lord’s Supper (1 Corinthians 10:17). A. A. Hodge said that if there is one God, one Christ, one Spirit, and one cross, there can only be one church. The believers of this one church are described by New Testament images such as ‘the salt of the earth’, a ‘holy temple’, the ‘new creation’, sanctified slaves, ‘sons of God’, and fighters against Satan.
They are many branches in one vine, many sheep in one flock, and many stones in one building. The church is ‘a chosen generation, a royal priesthood, a holy nation, a peculiar people; that ye should show forth the praises of him who hath called you out of darkness into his marvellous light’ (1 Peter 2:9).
Division
The church’s oneness in Christ is indestructible, for it comes from him. Her unity, however, can be disrupted by unfaithfulness to Christ and declension from the apostolic pattern of unity. And when it is, we should feel shame and grief.
She is afflicted by inattention to doctrinal and practical purity (1 Timothy 6:11-21); factionalism (1 Corinthians 3:1-23); lust for power (3 John 9); unwillingness to seek reconciliation (Matthew 5:23-26); failure to maintain church discipline (Matthew 18:15-20); and unwillingness to help needy believers (Matthew 25:31-46). Such sins tear apart the body of Christ, causing church and denominational splits.
Of the 23,000-plus church denominations today, more than 700 are Reformed. Nevertheless, even the multiplicity of church denominations caused by rifts between believers cannot divide the true family of Christ.
Brothers and sisters in a family may quarrel and separate, but they still remain members of one family. Likewise, the church is one body in Christ with many members (Romans 12:3-8), one family of God the Father (Ephesians 4:6), and one fellowship in the Spirit (Acts 4:32; Ephesians 4:31-32).
As Paul wrote to the Ephesians, ‘There is one body, and one Spirit, even as ye are called in one hope of your calling; one Lord, one faith, one baptism, one God and Father of all, who is above all, and through all, and in you all’ (4:4-6).
Spurious unity
A right understanding of the church’s oneness should help us avoid the kind of ‘unity’ that a church achieves at the expense of her confessions of truth. Some divisions are essential to keep the true church separate from the false. ‘Division is better than agreement in evil’, declared George Hutcheson.
Those who support spurious unity by tolerating error and heresy forget that a split based on biblical essentials helps to promote the true unity of the body of Christ. An organisation that moves away from faithful teaching, true worship, and obedient discipline, ceases to be a church.
As John Calvin said, ‘Those who wish to build the church by rejecting the doctrine of the Word build a pigsty, and not the church of God’. John Brown added, ‘The suffering of gross error in the church must be very sinful. It brings contempt on the oracles and ordinances of God, [and] gives Satan opportunity to employ ordinances and ministers as instruments of rebellion against God’.
Living in harmony
An appreciation of the church’s oneness should help us avoid denominationalism produced by splits over non-essential doctrines or egotistical differences. As Samuel Rutherford warned, ‘It is a fearful sin to make a rent and a hole in Christ’s mystical body because there is a spot in it’.
Such disunity offends the Father who longs to see his family living in harmony; it offends the Son who died to break down walls of hostility; and it offends the Spirit who dwells within believers to help them live in unity.
Church members must realise that they cannot touch any part of the church’s body without affecting the whole (1 Corinthians 12). Disunity affects the whole church, including its work of evangelism. In John 17, Jesus prayed for the unity of the church so men would believe that God sent his Son to be Saviour of the world.
Authentic church unity stands in startling contrast to the strife of the world, and is a sign to the world of the unity that exists between the Father and the Son. Christians therefore should work for unity in the church.
John Murray wrote, ‘If we are once convinced of the evil of schism in the body of Christ . . . we shall then be constrained to preach the evil, to bring conviction to the hearts of others also, to implore God’s grace and wisdom in remedying the evil, and to devise ways and means of healing these ruptures’.
Union of affection
We need to follow Matthew Henry’s advice: ‘In the great things of religion be of one mind, but when there is not a unity of sentiment, let there be a union of affections’. Authentic church unity is not promoted by exclusive denominationalism nor by an ecumenism that embraces even those who deny apostolic doctrine.
Rather, authentic unity is based on the work of the Spirit, who binds the church together and purifies it as Christ’s bride. The Spirit dwells within believers and endows them with the gifts to practise unity. That unity is a strong and attractive testimony of the gospel of Christ.
Consequently, Paul urged believers to be of one mind in the Spirit and to be joined and knit together so that they might grow up in every way in Christ (1 Corinthians 3:1-17; Philippians 1:27; Ephesians 4:1-16). Unity is not something to be created by Christians but something to be safeguarded by the church of all ages through the work of the Spirit.
Despite denominationalism and false attempts at unity, true believers will continue to be united as members of one body of Christ until the end of time, when every external division will disappear.
There will be no denominations in heaven. There, Christ’s prayer that all believers may be one will find its fulfilment (John 17:20-26). In heaven, the unity of the body of Christ will be resplendent (Revelation 7:9-17). What we now can hardly believe by faith, will then be gloriously evident by sight.
