Hmmm, let me think … no more than Saul of Tarsus (St Paul), is an educated guess, after all, there’s only so much damage any one man can do.
I suppose we need to expose the evils of the Church that canonises persecuters of the faithful like Saul/Paul, along with Christ-deniers like Simon Peter, not to mention shameless women of low morals like Mary Madgalene.
Yes, all this sarcasm has a point. A saint is not someone who is perfect or free of sin for their entire life - in fact it CANNOT be, since no-one IS remotely perfect or free of sin for their entire life.
All saints have been sinners as well, in their time. Moreover quite a few have been sinners on a grand scale, such as St Paul or St Mary Magdalene, and famously St Augustine of Hippo. There’s a saying ‘a saint is not someone who never sins, it’s someone who gets up again and repents each and every time he has sinned’.
You and I have far less knowledge of the life - and soul - of Pius V than the scholars who carefully examined in minute detail every aspect of his life before he was declared a saint. And that includes the one who was Devil’s Advocate - whose job was to carefully scrutinise Pius’ life and place on record every POSSIBLE occurrence in his life that suggested that Pius was NOT a man who was saintly.
All of the evidences for and against are a matter of public record - and still those who examined the cause for canonisation of Pius were overwhelmingly convinced that he did in fact lead a heroically virtuous life.