:::The question is not whether it is verifiable, but whether it is defining. Per WP:DEFINING, "if the characteristic would not be appropriate to mention in the lead portion of an article, it is probably not defining." Though I do not contest that Calvin is a saint in certain churches, I do not think if I were to describe who he is at a definition level, that I would mention him being a saint. In fact, it's trivial and I don't think the information belongs in the article at all.