Pope Leo XIII, Satis Cognitum (# 9), June 29, 1896: “No one who merely disbelieves in all these (heresies) can for that reason regard himself as a Catholic or call himself one. For there may be or arise some other heresies, which are not set out in this work of ours, and if anyone holds to a single one of these he is not a Catholic.”

What Francis Really Believes (4th Edition)