So, next guess is that he's deposed St. Pius X for the passage in his (allegedly his) Catechism.
People here have found the earliest prints of that Catechism and the reference to BoD is not in there, and nobody could track down when it was first added. It underwent multiple revisions by many hands, including after his death. Finally, even if he did believe in BoD, BoD itself is not heretical, as the Church declared doctors at least three men who held that opinion: St. Thomas Aquinas, ST. Robert Bellarmine, and St. Alphonsus.