One year ago, I reported that many Protestants are ready to “cross the Tiber” into Roman Catholicism. The expression “crossing the Tiber” refers to fording the river that runs alongside Rome, symbolic of the barrier between Rome and Protestants. With grief, I had to report that even leaders in our mother church are talking about making the crossing.1 Some church leaders are sending not-so-subtle messages to members: It is permissible, and probably time, to unite with the Catholic Church. One Calvin Seminary faculty member wrote that Protestants and Catholics are “pilgrims on the same journey, serving one Lord with one...