Viewing the church with the eyes of faith

Martin Luther writes:

This article, "I believe in the holy Christian Church," is as much an article of faith as the rest. This is why natural reason cannot recognize it, even if it puts on all its glasses. The devil can cover it over with offences and divisions, so that you have to take offence at it. God too can conceal it behind faults and shortcomings of all kinds so that you necessarily become a fool and pass false judgment on it. Christendom will not be known by sight, but by faith. And faith has to do with things not seen

("Preface to the Revelation of St. John [II]" (1546), in Luther's Works, Vol. 35, p. 410)

This connects with the Magisterial Reformers understanding of the marks of the church. Calvin writes:

Wherever we see the word of God sincerely preached and heard, wherever we see the sacraments administered according to the institution of Christ, there we cannot have any doubt that the Church of God has some existence, since his promise cannot fail, "Where two or three are gathered together in my name, there am I in the midst of them" (Mt. 18:20)

[...]

We have said that the symbols by which the Church is discerned are the preaching of the word and the observance of the sacraments, for these cannot anywhere exist without producing fruit and prospering by the blessing of God.

(Institutes 4.1.9-10)

The reason that the preaching of the word and administration of the sacraments were identified as marks of the church was because of faith that these would not be without effect. God had promised that his word would not go forth without achieving his aim, so that must be the case. We may see evidence to contradict this but we have faith in God and his promises.

I need to do some thinking on how this relates to the renewed interest in the church as community. We are rediscovering that we are not independent souls that do not need each other but were saved as a body. However, this seems to be happening while we at the same time we judge that the Church is something we can define, see and touch. Today we rarely hear about the Reformers' marks of the Church, although we often hear about the mark being love.

I see both viewpoints as true to the Bible and experience, but I am concerned that I don't know how to relate them to each other. I suspect it has to do with eschatology.