“In this case, I think we have to recognize that the Holy Father has plainly erred. Catholics cannot promote the legalization of same-sex unions. But we also have to be clear that he isn’t changing the teaching of the Church on homosexuality or same-sex unions in any way. He can’t do that, and he has himself repeatedly upheld the teaching – including in a formal encyclical, Amoris Laetitia, a few years ago”