In 1888, Bavinck lectured to the students of the theological school in Kampen – the title was “The Catholicity of Christianity and the Church.” You can find it on the internet in places and in the Calvin Theological Journal 27/2 (1992). It is classic Bavinck: gospel centered, humble, and “churchly.” I like what he says on the purity of the church (he closes the lecture with this).
…The one universal Christian church comes to more or less purity of expression in individual churches, in the same way the one universal Christian truth comes to more or less pure expression in the various confessions of faith. There is no universal Christianity present above the confessional divisions but only in them. No one church, no matter how pure, is identical with the universal church. In the same way no confession, no matter how refined by the Word of God, is identical with the whole of Christian truth. Each sect that considers its own circle as the only church of Christ and makes exclusive claims to truth will wither and die like a branch severed from its vine. The one, holy, universal church that is presently an object of faith, will not come into being until the body of Christ reaches full maturity. Only then will the church achieve the unity of faith and the knowledge of the Son of God, and only then will she know as she is known.”