The Church is not the source of the witness; rather, it is the locus of the witness. The light cast by the first rays of the morning sun shining on the face of a company of travellers will be evidence that a new day is coming. The travelers are not the source of that witness but only the locus of it. To see for oneself that it is true, that a new day is really coming, one must turn around, face the opposite way, be converted. And then one’s own face will share the same brightness and become part of the evidence.
The Gospel in a Pluralist Society p.120