… as explained by Andrew Root.  According to Root, in CD 4.3 Barth argues the following about the church:

1. The world would be lost without Jesus Christ.
2. The world would not necessarily be lost without the church.
3. The church would be lost of it had no counterpart in the world.

Humbling and thought-provoking.

Since I haven’t exactly started reading Church Dogmatics and expect it to be a few years after I start reading them (if I ever do) until I will find my way to 4.3, for now I’ll take Root’s word that this is Barth’s argument.