Character Analysis
We'd like to suggest that Silence might be more accurately titled Silence III: The Search for Father Ferreira. Okay, we're kidding—but only sort of. The fact is, despite his constant claims to the contrary, Rodrigues's only reason for visiting Japan is to learn the truth about his former teacher. Once he does learn the truth, however, the poor guy might wish that he never left home in the first place.
Faith No More
Rodrigues is deeply disturbed by the idea that Ferreira might have renounced the faith. This is a personal issue for him, as Ferreira had taught him and his bros at the seminary. In a way, Ferreira's failure would reflect on them—after all, could they really be good priests if the man who taught them was so bad? They don't even want to consider the possibility. On top of that, if Ferreira has renounced his faith, then how can they really stay secure in their faith?
As is often the case, reality is stranger than anything these guys could have imagined. Ferreira is indeed alive and well, but he "has taken a Japanese name, and [...] lives in a mansion in Nagasaki together with his wife" (5.104). After renouncing his faith, Ferreira was renamed Sawano Chuan and integrated into Japanese society by the same people who had tortured him. Rodrigues is understandably angry—not to mention confused—by this mind-blowing revelation.
Turning Japanese
Rodrigues may not be happy when he learns the truth, but we'd be lying if we said we didn't get Ferreira's perspective. After spending so much time as a missionary, Ferreira realized that "the Christianity [...] brought to Japan has changed it forms and [...] become a strange thing" almost entirely divorced from Western Catholicism (10.55). We can certainly see evidence of this in Rodrigues's interactions with the Japanese Christian community. Basically, the Catholic Church's foray into Japan was not without its failures, so it's hard to blame Ferreira for losing his motivation as those failures stack up
Oddly, however, Ferreira's main motivation for renouncing his faith is love. As he tells Rodrigues, "for love Christ would have apostatized [...] even if it meant giving up everything he had" (8.100). Ferreira had actually endured several days of brutal torture without breaking a sweat, but it was the needless persecution of Japanese Christians that finally made him change his tune.
Although it's hard to get a glimpse of Ferreira free of Rodrigues's filter, the former priest shows that he still has love in his heart, even if his faith has already faded. At the same time, isn't love the basis of faith? It's what old J. C. was all about, after all. So did Ferreira also, in a way, gain in faith by renouncing it?