A common distinctive of Protestant ecclesiology is to distinguish between the invisible and visible church. What this distinction is meant to communicate is that within any church gathering, there will be a varied assortment of people: some will be true believers; but others will be unbelievers, professing believers, hypocrites, etc. What we see, what is visible, is a bunch of baptized professing Christians. However the reality is that only a segment are truly regenerate, united to Christ, part of Christ’s body. But this group is not perceptible to the eyes; ergo, the invisible church verses the visible. We cannot see who’s who.
Many do not like this distinction between visible and invisible because it creates an impression what’s really important is the invisible, spiritual body of believers. The visible, ecclesial, hierarchical, sacramental, is really irrelevant to the Christian life. What really matters is the heart, that I love Jesus. Another issue brought up is that this theology creates a sort of disdain for the sacraments. “Well I know he was baptized, but until I see fruit I’m still not sure he’s the real deal!”
Douglas Wilson, while understanding the distinction, proposes that we designate another term for this reality. He suggests calling it the “historical church” verses the “eschatological church”. There are those who are in the church now in history, verses those true believers who will be in the church in eternity. What this does get away from the anti-establishment anti-sacramental stuff. And while at times I understand and even like his suggestion, I still think the visible/invisible distinction is important. And actually, that distinction is there in the scriptures.
Turretin explains the distinction from scripture in his Elenctic Theology, volume 3:
It is one thing to be in the church by a visible communion and to use the same profession and the same sacraments; another to be of the internal and invisible communion of the church and to be bound together by the same bond of faith and Spirit. I grant that [unbelievers] are in the church in the former sense, but I deny that they are in the latter. Christ denies it “Ye are of your father the devil! (Jn 8:44); “Ye are not of my sheep” (Jn 10:26). John denies it, “They were not of us” (1 Jn 2:19). And as “all are not Israel, who are of Israel (Rom 9:6), i.e., they who will spring from Israel according to the flesh still are not the true Israel according to the Spirit, to whom the promises are made; thus neither are all who are in the church of the church (pp 21)
Turretin first brings out the Pharisees. The Pharisees, for all intents and purposes were part of God’s people Israel: they participated in the sacraments, sacrifices, worship, they taught and led; and yet Christ calls them children of the devil. They were in Israel but not truly Israel. Paul’s distinction of the two types of Israel from Romans 9 is also telling: there were those who were part of Israel by birth but not by faith, and so they were members merely externally. The point here is that there are those who are in the visible assembly only; but they do not have true faith, and so they are not part of the church truly. They have merely the external membership which does not save.
Paul accounts for this when he says in Romans 2:28-29
For no one is a Jew who is merely one outwardly, nor is circumcision outward and physical. But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. His praise is not from man but from God
Paul says that a true member of the church is one who is circumcised of the heart, not just the flesh. That is not to say that he degrades the sacramental aspects of church life. He says in Romans 3:1 that to be externally circumcised is of benefit “in every way”. We don’t want to do away with the visible aspects of church practice. The point here is to say that it’s possible to participate in church life without actually having a heart change. This means that your membership is only skin deep. It hasn’t reached the recesses which matter the most. This is the reality: true church membership is that membership which participates in both the invisible and visible aspects of church life. It receives the sacraments and experiences spiritually what they convey.