They would think he's being honest. This kind of language was standard Protestant fare up till very recently.
Frankly, it is psychologically necessary. The Reformation's break from Rome was SO complete, that the Reformers HAD to believe that what they were leaving *was just that darn bad* to justify what they did.
Because if--mirabile dictu--it *wasn't* all that bad, then somebody down the line made a BIG BIG mistake. :)
Well, Claud, remember that the Catholic church also failed to reform some ridiculous practices when called upon by a priest to do so; I picture the Pope’s white elephant in parades while the church split and financial concerns over stopping indulgences . . . I’m not a big historian of the Church but I have a hazy view of a sort of Nero of Christianity, fiddling while the Church burned, so to speak, in Leo X. There was hardening was on both sides when the reverse was needed in light of Christ’s prayer for unity in the Church.