> authentic Christian faith is not an arbitrary faith in anything you please

But he's not talking about an arbitrary faith. He's talking about faith in the capacity of priests -- clearly a relevant subject. And there are, indeed, _preambula fidei_ here: that the priest was taught in seminary, that the priest was approved by the Church, that the priest (through the bishop who ordained them) participates in a line of apostolic succession going back to Jesus, etc.