Commentary Par XIX 103-105

The Eagle's words are pellucidly clear; nevertheless, some readers contrive not to understand them.  Salvation without belief in Christ is simply not possible.  We should tuck this notice away in order to reexamine it in the light of the salvation of both Trajan and Ripheus in the next canto; in the light of this absolute qualification, their salvations seem dubious, at the very least.

For an excursus (in English) on the concept of implicit faith, which alone can make a bit more understandable Dante's unshakable embrace of the Church's firm ruling in this matter, see Carroll (DDP Carroll.Par.XIX.79-84).