Ephesians 5:28 So husbands ought also to love their own wives as their own bodies. He who loves his own wife loves himself; 29 for no one ever hated his own flesh, but nourishes and cherishes it, just as Christ also does the church, 30 because we are members of His body.
Col 1:24 Now I rejoice in my sufferings for your sake, and in my flesh I do my share on behalf of His body, which is the church, in filling up what is lacking in Christ’s afflictions.
Westminster Confession of Faith Chapter 15
I. 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 fullness of Him that filleth all in all.
II. The visible Church, which is also catholic or universal under the Gospel (not confined to one nation, as before under the law), consists of all those throughout the world that profess the true religion; and of their children: and is the kingdom of the Lord Jesus Christ, the house and family of God, out of which there is no ordinary possibility of salvation.
III. Unto this catholic and visible Church, Christ hath given the ministry, oracles, and ordinances of God, for the gathering and perfecting of the saints, in this life, to the end of the world; and doth by his own presence and Spirit, according to his promise, make them effectual thereunto.
IV. This catholic Church hath been sometimes more, sometimes less, visible. And particular Churches, which are members thereof, are more or less pure, according as the doctrine of the gospel is taught and embraced, ordinances administered, and public worship performed more or less purely in them.
If the essence of the true Church is spiritual, that is, it is the very body and bride of Christ, then we must be very careful about letting visible things take priority of that in any way. The WCF (as seen in the sections of chapter 1-5 above) steps far too close to that line (at best). The life of the Church is Christ Himself and that is the spiritual Church. People are united to Christ spiritually and not visibly. The professing church will have no life other than when it comes into contact with the true and living Christ and that can only be spiritually. As long as the professing church operates by visible things, it cannot have the life of Christ.
When a professing church operates under the notion of a visible church, it is not operating under the truth of faith which operates by things that the eyes cannot see. The Gospel must be preached in a spiritual way and the Gospel must be preached in such a way that the natural eye can see that it is blind and needs grace to open the eye. The visible church must operate in a way that points people to the spiritual realm and points people to the invisible things as more important and more real than the physical realm. The kingdom of the Lord Jesus Christ is over spiritual things and it is over His spiritual subjects. The kingdom of the Lord Jesus Christ is over the regenerate by which they must be born from above to even enter His kingdom. The kingdom of Christ does not consist of those who profess the true religion, it consists of those who have the true religion in their hearts.
It seems to be self-evident that the truth of God is at a low ebb in our nation today. There are many who profess Christianity, but according to the power it has over their lives it appears that few have Christ in truth. It would appear that many are satisfied with knowing that they are in the visible church and they think that they are in the invisible church and as such in the kingdom of Christ. This is terribly confusing to people. The people need to hear a clear distinction between the spiritual kingdom of Christ and that which is not of Christ. The people need to hear that they must really and truly be born from above if they are to enter the kingdom, not just that they need to belong to the visible church.
While it says that the professing churches are more or less pure depending on the gospel that is taught, I would argue with Luther that if they do not preach a pure Gospel they are not preaching the Gospel at all. If they are not preaching the Gospel, then they are not part of the true Church and no true Christian should be part of a non-Church. The issues involved here are quite enormous and even vital. This is not just some minor thing, it is very important. There is no such thing as a true Church which does not preach the true Gospel. Regardless of whether it holds to a good or even great confession, and regardless of whether it has the true Gospel in the confession, it must preach the true Gospel or it is not a true Church. Being part of a professing church that has a great confession is not determinative of whether that professing church preaches the true Gospel. Preaching the Gospel is absolutely necessary in order to be a true Christian and to be part of the true Church.