Back when what seemed a long time ago, I was criticized for my focus on the invisible church. That criticism was done by a Baptist. After going through seminary, I have come to see why such criticism makes sense in the Baptist scheme of things.
On the nature of visible things and the invisible reality behind those things, there has been theories about how they relate to each other. In the doctrines concerning sacraments for example, the issue is the relation between the physical sign (signum) and the thing signified (res significata). So how does the bread in the Lord's Supper relate to the Body of Christ it signifies? How does the water in baptism signify regeneration, the death and being borned again of the believer in union with Christ? In all these, there is the physical sign, which signifies the spiritual reality behind it.
In traditional Roman Catholic sacramentology, the sign IS the thing signified. Thus, in the Mass, one actually eats the real Body and drinks the real Blood of Christ, as the elements are transubstantiated into the body and blood of Christ. At baptism, the water actually regenerates the person being baptized, because the sign is the reality, so application of the sign ex opere operato accomplish its purpose. In the Zwinglian view, which Baptists (traditionally) and most Christians today hold to, the sign is separated from the thing signified. Therefore, a person can eat the bread and drink the wine, yet not actually eat and drink the Body and Blood of Christ. Baptism can be just washing, a pouring of water on the person, which is why baptism can be re-administered since the previous baptism, for whatever reason, is considered invalid. It is no wonder therefore that the Swiss Anabaptists came out under Zwingli's teaching, for if baptism has no spiritual reality attached but is merely an oath pledge of faith, then certainly babies can't take that oath pledge, and infant baptism is thereby invalidated, thus all persons baptized as infants are to re-baptized (or undergo adult baptism).
In contrast, the Reformed understanding is that the sign and the thing signified are related to each other. They are not equated, neither are they separated. Distinct but not separate. Thus, the bread is bread, but there is a relation with the Body of Christ so that all who eat of the bread partake of the Body of Christ, either unto blessing or unto condemnation. Thus, the water is related to regeneration, so that all who partake of baptism have the sign of regeneration, and thus show forth their regeneration in time, or suffer the curse of covenant breaking. In the Reformed system, there is always a relation between the sign and the thing signified, a relation which is rejected by Baptists in general.
So what does this have to do with the Visible/ Invisible Church distinction? Like the relation between sign and thing signified, the Visible Church and the Invisible Church are distinct but not separate. They are not equated to each other, neither are they separated to the extent that one can discount the Visible Church while claiming to be a member of the Invisible Church.
We see this dynamic at work in Baptist and broad Evangelical circles. On the one hand, we have those who are so focus on the "Invisible Church" that they reject the Visible Church altogether, or downplays it. Here we have people like John Nelson Darby and the Plymouth Brethren, and here we could put Frank Viola as well. The Visible Church disappears altogether, for what God is focused on is the Invisible Church. On the other hand, we have those who move towards the equating of the two. In reaction against the focus on the Invisible Church we have those who focus on the Visible Church. Thus, we have people like Frank Turk, whom I have debated in the past. Such baptists react against the low view of the Visible Church for its other extreme. In the case of Frank Turk, that means separation from any professing church is out of the question, presumably as long as it is called a church. For such people, separation equals the horrors of J.N. Darby, C.I. Scofield, and all the problems that attend them. Ironically, because their paradigm is unreflective and reactionary, they have replaced a separation of res et signum for an almost equation of res et signum, such that the Visible Church IS the Invisible Church in all but form.
That is why there is nothing wrong to focus on the invisible church, when it is done right in the Reformed paradigm. In fact, focusing on the invisible church should be the case, for that is what the Visible Church strives to be. In such a paradigm, there is no question about being a member in a Visible Church. The visible Church is not seen as an organization we join in obedience to God's command, something believers do after salvation. NO! The visible Church is the mother of believers. We are birthed through her and in her. She nourishes the souls of believers through her offices. The Church is NOT a place for one to go to "do ministry" and "serve God." The Church is just there to nourish the saints for works of service to others. Normally, a believer is a member in a visible church, and that is it!
It is no surprise that Baptists generally can't get their ecclesiology right, for they start with a wrong view of the relation between sign and thing signified, which influence their view of the relation between the Visible and the Invisible Church. With this wrong view, those who react against the separatists just swing to the opposite extreme, and thus almost equate the two. In both of these extremes, God's people lose out. In the former, they separate themselves from Christ's church, supposing themselves to be the "true invisible church." In the latter, they let themselves be unequally yoked with false churches, being spiritually malnourished and told they must continue in their sorry state because Christ told them to. Unfortunately, beliefs HAVE consequences, and none seen more practical than in ecclesiology.
The Visible/ Invisible Church distinction is a distinction, not a separation. We should not equate them, nor separate them. Only when we hold that they relate to each other can we do justice to what Scripture instructs us concerning the church.