On page 13 of his Reformed Dogmatics: Volume Five, Geerhardus Vos asks this interesting question: “Is it easy to give a definition for ‘the church’?”. Vos answers candidly: no.
Just pages before, he gave the instances and meanings of the NT usage of the word “church”. The most common Greek word used is, of course, ekklesia. It is common to define this term as those “called out of”. But there are several contexts in which the “called out ones” are defined.
For instance, there is the idea of the universal church: those called out of sin to union with Christ. “In the first place, it is those called by Christ and to Christ” (p 10). This has no bearing on local assemblies, but rather to the mystical reality of all the elect gathered and united to the head. Paul commonly uses the metaphor of body and head in terms of the universal church, ekklesia catholikos (catholic church). This is the church in its most comprehensive context: those in earth and heaven, united to Christ the head and receiving the benefits thereof.
However, the term ekklesia has yet another usage in the NT; and that is of the local assembly. “The second meaning of the word “church” is that of the local, visible church — thus, the gathering of believers who meet in a particular place or city” (p 11). Vos lists off numerous references in the NT of the church gathered in Antioch or Asia etc. What this means is that ekklesia can refer to a specific gathering of people, and not to the comprehensive reality of the catholic church.
For this reason, Vos explains, “the matter [of the church] is considered from differing viewpoints” (p 13). He mentions three viewpoints, or starting points, from which one may define the church:
a) From election: Some say that the essence of the church is not latent in any external institution but in internal unity with Christ (p 13)
Vos reasons that this is the opposite view of the strictly sacramental churches: some say that those who partake of baptism are ipso facto part of the church. This reasoning is “from the outside in” (p 13). However, reasoning from election is starting from the opposite end: from the inside out. The elect are those inwardly called and regenerated and thus are part of the external body. But, says Vos, those elect not yet born or those still unbelieving cannot properly be said to be part of the church. They have yet to be implanted into Christ, yet to repent and believe, and are by definition outside of the church!
There is another option, noted above:
b) From baptism: Engrafting into the body of Christ and belonging to it are outwardly signified and sealed in baptism. Thus we no longer have to do with the invisible church, but with a visible form that it assumes. (p 14)
This reasons not from election but from the sacramental life of the church: those participating in those ordinances are said to be part of the ekklesia. The difficulty lies, Vos rightly reasons, in what he calls a “valid baptism”. There are some members that receive baptism that “it would be difficult to call…believing brothers” (p 14). Vos later goes on to distinguish rightly between one who has received the sign of baptism and one who has received the grace of baptism. The two often do not meet, although ideally they should! Just as some Jews received circumcision without receiving the inward reality of “the circumcision of the heart”, so too many receive the sign without the seal. And although one cannot go on to judge the genuineness of a Christian’s baptism, nevertheless, this does not guarantee salvation.
As an aside, this was one of the Reformation’s sacramental emphases: sacraments, although salvific, are not automatically salvific. The Westminster Confession talks about the “efficacy of baptism”, but clarifies by saying:
Although it is a great sin to contemn or neglect this ordinance, yet grace and salvation are not so inseparably annexed unto it, as that no person can be regenerated, or saved, without it: or, that all that are baptized are undoubtedly regenerated (28.5)
One might interpret this article by saying that sacraments are indeed efficacious but must be received rightly. Infants admitted to baptism, for instance, are indeed participants in grace, but if one rejects or even neglects baptism through unbelief or sin, that baptism is to no effect. Baptism is not an automatic grace.
Vos moves on to his third option for defining the church:
c) Finally, some have begun with confession. Insofar as confession is the principal external means to manifest the invisible essence of the church and to cause it to materialize outwardly, it already belongs under the preceding approach. Confession, however, is also a bond that binds the members of the church together in the external form of the church. To this extent, it is what is characteristic for the visible church in its institutional form (p 14)
Put another way, confession or outward profession, enables the reality of the inward invisible church to become visible in an institutional form. It brings invisible and visible together. Vos holds this to be the most ideal in defining the ekklesia. And of course, those who make their profession have already been part of the elect from all of eternity and presumably have already participated in the sacramental life of the church.
Having this ideal, Vos transitions into his next section by clarifying that this struggle for a definition of the church is why the Reformed hold to a distinction between the invisible and visible church (p 15). “One may not place them beside each other dualistically as if they were two churches”, however (p 18). The invisible and visible church are two sides of the same church (p 18). But this remains a reality: one may belong to the visible institutional church without being vitally united to Christ; and likewise one may not belong to the institutional church and yet still, in God’s grace, united to Christ.