Karl Barth's Church Dogmatics is helpfully read as an attempt to outline Evangelical (meaning, Reformation) theology in contrast with Roman Catholicism on the right and Liberalism (what Barth calls Neo-Protestantism or Modernism) on the left. Barth sees Rome and Schleiermacher as being, despite their many differences, very similar at the end of the day - or at least similarly opposed to the fundamental basis of Evangelical doctrine. That fundamental basis is a free Bible, a Bible which shows itself to be the Word of God, which does not have to be defended or to have its authority discovered in another place. For Rome, the authority of the Bible derives (in practice, if not in theory) from the church, which claims the exclusive right through its teaching office to offer interpretation of Scripture; for the Neo-Protestant, such authority as the Bible is thought to have is tied to the religious self-consciousness of the reader. In neither case is Scripture regarded as free, self-authenticating, and able to stand over against the reader as the Word of God. (It is, of course, all these things despite the way in which it is regarded, and God is able to make it evidently all of these things even within Romanism and Modernism. But it is not so regarded).
In contrast, Evangelical theology points to the Bible as its very basis, on which everything else if founded. "That is to say, we have not in any sense or in any way to answer for it that the Bible is really God's Word... We can say no more than this, that the Bible can answer for itself in this matter".
But the key thing for me is that, in contrast to the pre-suppositionalist apologetics of today, Barth does not see this position as a strong one. It is desperately weak, and throws one open to all sorts of accusations. Is it not utterly arbitrary? If it is not, that does not depend on us but on God. Where does our assurance come from? We cannot say, but then we do not want to build on our assurance but only on the thing itself.
Is it perhaps a special spiritual experience that has led us to this? Is this "a secret appeal to a special grace"?
Not at all - "this opposition [to Rome and Schleiermacher] seeks to be nothing of all that, nothing special, no prophecy or apostolate, just a very earthy, harmless, ambivalent matter, devoid of all mystical splendour or mystery, just a little Protestantism, a sign to which we can give no signifying power, which may in fact be opposed or totally overlooked or misunderstood, and about whose unimportance among all the other signs in which the world and the church are so rich we have no illusions."
And the irony is that we are talking about the very power of God for salvation! But that power, that Word, is not under our control, cannot be advanced by us, can only be pointed to as the sign which God is able to turn into that which it signifies, the word which he is able to make into the Word.