He does not write alone...

He does not write alone, as an isolated individual; he writes with the assistance of the Church, of people who help him to deepen the faith, to enter into the depths of his thought, of his rationality, of his profundity. And this is very important: Peter is not speaking as an individual, he is speaking ex persona Ecclesiae, he is speaking as a man of the Church, as an individual of course, with his personal responsibility, but also as a person who speaks on behalf of the Church; not only private and original ideas, not as a 19th-century genius who wished to express only personal and original ideas that no one else could have expressed first. No. He does not speak as an individualistic genius, but speaks, precisely, in the communion of the Church.... This does not mean to say a word that is his alone, but one that really contains the waters of faith, the waters of the whole Church, and in this very way gives fertility, gives fecundity. 

Pope Benedict XVI, in his address to seminarians on February 8, 2013, three days before he was to resign, spoke on 1 Peter 1:3-5.  Sources: Catholic News Service, Transcript of the talk.