Turretin seems a little put out in having to answer this question. He makes it clear that it is a question that arises in a primarily polemic context. Roman theologians of his time claim that Protestantism is false because it did not exist prior to Luther; Protestants retort that it existed, just not visibly. This is because “the true church [is] not to be measured by an external profession or subjection to the Roman pontiff, but by faith and internal piety alone” (18.7.2). He even has a nice quote from Bellarmine that seems to show agreement!
For Turretin, the church’s two-fold condition as both visible and invisible arises from the two-fold nature of God’s call: the external call made through visible instruments, and the internal call of the Holy Spirit (18.7.4). This is an interesting move because these are overlapping sets that are nevertheless unable to be reduced to either side. One might even go so far as to call this overlap between the visible and invisible church a paradoxical identity, but I digress from Turretin…
There are three ways in which we can think the church’s invisibility, according to Turretin’s schematic (18.7.5). First, there is the invisibility of form or essence; second, there is the invisibility “parts” (i.e., of the membership of the true church as opposed to the visible membership of the visible church structures); and third, there is the invisibility of the “signs” and “sacred rites” (i.e., the efficacy of the sacraments; Turretin readily admits that they are visible by their own nature). This allows Turretin to narrow the question at issue—it is the first mode of invisibility that is truly at issue. He restates the question: “Is the church, composing the mystical body of Christ, rightly said to be invisible, not by an invisibility of parts or of material or of signs, but by the invisibility of internal form and as such” (18.7.6)? In other words, Turretin focusses the question on the church’s very being (“form” or “essence” in his parlance).
It is at this point that Turretin starts giving arguments for his position, and he provides seven. Briefly: First, Turretin says that his point is proven by his discussion of what it means to belong to the church in question 4. Second, he does some quick and dirty exegesis to show that “the truth of Judaism” is also an internal, visible matter (18.7.8). Third, everything that “constitutes the church properly so called are internal and invisible: election and effectual calling, union with Christ, the Spirit, faith, regeneration and the writing of the law on the heart, the reasonable and spiritual worship” (18.7.9). The corollary is that people don’t belong to the church simply as physical beings, but they do so as spiritual beings who are “renewed by the Spirit.” Fourth, and this one is the kicker for me, “the head of the church is invisible; therefore its body also is invisible” (18.7.10). And lest anyone argue that Jesus was a physical being on earth, Turretin points out that while that is true, Jesus’s being the head of the church is not a function of his physical being. His headship is a spiritual reality, and so the church’s being as his body is also a spiritual reality. This is, in effect, the application of Chalcedonian logic to the being of the church: just as you can’t read Jesus’s divine nature off the appearance of his human nature, so also you cannot demonstrate the church’s true being by pointing to its external manifestation. This also made me think of how Barth speaks about Jesus Christ as himself the being of the church (in CD 1.1). Fifth, and this is a nice little rhetorical move, the creed asks us to confess belief in the church and, as Hebrews 11.1 says, faith deals with things unseen! Sixth, “the church is the kingdom of God” (18.7.12). We find in Turretin here the sort of realized eschatological for which the Reformed tradition is famous—namely, the idea that the kingdom of God is a spiritual reality experienced by the church as the body of Christ its head. One misses the sort or eschatological proviso that 20th century Protestant theology has been so keen to emphasize. Of course, we get citations of passages like Luke 17.21. Seventh, true worship of God is in spirit and truth (Jn. 4.23).
At this point Turretin, as is his wont, moves to explicate further sources or evidence for his position in general. Often this means that he is dealing with counter arguments. I want to briefly highlight five of these further points:
18.7.15 — Turretin brings up the “city on a hill” passage (Mt 5.14) and, in dealing with it, reveals a deep tension in the Reformed tradition: “Hence he wishes to show them how anxiously they ought to strive not to do anything which can offend men, but rather that they should diligently care that the light of their good works may shine before men that they may be influenced to glorify God.” It doesn’t seem to occur to Turretin that these good works might make folks uncomfortable, and perhaps should make folks uncomfortable.
18.7.17 — Here he uses the analogy from circumcision to baptism, saying that in each case it was not the external rite that mattered but an internal work of the Spirit. Given my work on infant baptism, I wanted to flag this.
18.7.19 — This point is interesting to me because Turretin builds of Calvin, without citing him. He’s speaking about the invisibility of faith, and argues that it isn’t important to be able to tell which people are true believers in order to identify the true church (which you can identify through the usual marks). Rather, one should exercise “a charitable judgment” with reference to those who claim to be Christians. Calvin uses this same phrase in Institutes, 4.1.8.
18.7.21 — The spectre of Mt. 16.18 rears its head, and Turretin argues that it is not Christ’s physical body that provides the foundation of the church, nor Peter’s physical existence, nor even Peter’s confession as a physical phenomenon, but rather the truth attested by this confession. Thus the foundation of the church is invisible. This ties in with point four above.
18.7.22 — This may be the best bit of the whole section, for here Turretin explains the difference between earthly kingdoms and the kingdom of God: “Hence it does not follow that if republics are always visible or consist in an external and visible government, that therefore the church must also.” Indeed, he has now argued at length that the church does not so consist. “Since its formal reason is in the mystical union of believers with Christ and with each other, the external union alone with him does not make anyone a member of the church; nay, without the latter union, true believers who dwell in separated places are members both of Christ and his church.” It is something of an extension of Turretin’s logic here, but one consequence of this – for my money – is that Reformed theology must have serious reservations about postliberalism and its turn to the culture or linguistic world of the Christian community. These are externals, and therefore not essential to the church. In theory, based on Turretin’s position, we can imagine the church taking any number of different physical / material / cultural shapes while remaining the one church because of its internal, invisible, being.