The type of the Church which Luther chooses and with him Zwingli and Calvin .against Evangelical Radicals, is the ecclesiastical in contrast to the sectarian type.
You know all this distinction from Troeltsch, and it is a very good distinction. It is a distinction between a Church which is the mother, out of which we come, which always was there, which we have not chosen, to which we belong by birth and if we awake out of the dimness of the early stages of life, we can perhaps reaffirm that we belong to it in confirmation; but we already belong to it objectively.
Now this is quite different in the churches of the radical Enthusiasts where the individual deciding that he wants to be a member of the “church” is the creative power of the church. The church is made by a covenant by the decision of individuals to, make a church, namely an assembly of God. So here you find everything is dependent on the Independent individual who is not born from the Mother Church, but who produces active church communities. These differences are very visible if you come from the Continent, where we have the ecclesiastical, while you have, even in the old denominations here the sectarian type.
Luther’s distinction between the visible and the invisible Church :is one of the most difficult things to understand. The one way in which you can understand it immediately is to understand when you hear those words that they are the same Church, they are not two Churches. This is the main point we mus t make. The invisible Church is the Spiritual quality of the visible Church. And the visible Church is the empirical and always distorted actualization of the Spiritual Church.
So they are not two realities. They are one and the same. This Was perhaps the most important point of the Reformers against the sects. The sects wanted to identify the Church according to its visible and its invisible side. The visible Church must be purified, purged as all totalitarian groups call it today from everybody who is not Spiritually a member of the Church. This presupposes that you know who is Spiritually a member of the Church. And this presupposes judging, looking into the heart, into which God alone can look. This of course produces something which the Reformers could not accept, because they knew that there is nobody who does not belong to the “infirmary” that is the Church, as they called it, the infirmary which is the visible Church. But this “infirmary” is for everybody; nobody can get out of it definitely. And therefore everybody belongs to the Church essentially, even if he is Spiritually far away from it.
Now what is this Church? The Church is an object of faith, according to its true essence. It is, as Luther said, “hidden in spirit.” It is an object of faith. When you see the actual working, the ministers, the building, the congregation, the administration, the devotions, etc., then you know that in this visible Church, with all its shortcomings, there the invisible Church is hidden. It is an object of faith, and it demands much faith, if you look at the life of the ordinary present-day congregations, and have the faith that in this life, which is by no means a life of high standing, in any respect, the Spiritual Church is present. And you can believe it only if you believe that it is not the people who make the ‘Church, but it is the foundation, which is not the people but the sacramental reality, the Word, which is the Christ. Otherwise we would despair about the Church.