It is certainly no geographic accident that Barth and Balthasar were in Basel at the same time and knew each other. If memory serves me correctly, Balthasar lectured Barth's students on the theology of Karl Barth! His little book, The Theology of Karl Barth remains a very good critical introduction to Barth's highly influential theology. Balthasar questions whether Barth's proposed analogia fidei was really all that different from the classic analogia entis that Barth sought to displace.
In his treatise on St. Paul's Epistle to the Romans, Barth wrote:
A man may be of value to another man, not because he wishes to be important, not because he possesses some inner wealth of the soul, nor because of something he is, but because of what he is - not. His importance may consist in his poverty, in his hopes and fears, in his waiting and hurrying, in the direction of his whole being towards what lies beyond his horizon and power. The importance of an apostle is negative rather than positive. In him a void becomes visible. And for this reason he is something to others: he is able to share grace with them, to focus their attention, and to establish them in waiting and in adorationToo often our faith is driven by the personality and charisma of others, especially in a media-driven day like our own. I am always surprised by how shocked and disappointed people are when religious media personalities fall, fail, are revealed to be fakes and phonies. I think in this insightful passage Barth offers us great insight as to why, at least among Christians, this is the case. When it comes to the use of electronic media, I think being controversial for the sake of being controversial, or, worse yet, trying to generate attention by providing a spectacle (which I would distinguish from being provocative by intent) is like spitting in a pond full of carp. The response is gross, but fascinating to watch because it appeals to our morbid curiosity.
I think here Barth truly gets at the essence of the apostleship of St. Paul, which, in his own day, was a difficult battle, in which Paul refused to assert himself in certain ways, relying instead on the Holy Spirit, and remaining true to his calling as an apostle, which was not accepted by all.