Updated

Pope Francis has received an unlikely anniversary gift from his predecessor.

Retired Pope Benedict XVI has publicly dismissed as "foolish prejudice" those who say Francis has no theological heft and represents a rupture from his own papacy.

The occasion was the release of a new volume of Vatican-curated books on "The Theology of Pope Francis," published as Francis marks his fifth anniversary Tuesday.

Benedict wrote a letter welcoming the volume, saying it "shows Pope Francis is a man of profound philosophical and theological training and helps to see the interior continuity between the two pontificates, with all the differences in style and temperament."

Francis frequently downplays the work of theologians, and his critics point to his simple speaking and writing style as evidence of a doctrinal deficit.