This is simply false. The violence was roughly equal on both sides and it was part of the process of consolidating absolute royal power. You apparently know nothing of the sadistic violence of the Calvinist “brigands” who savaged northern France and Belgium and southern France, burning, raping, boiling alive, castrating, defecating in church sanctuaries, flaying alive and so forth. Henry VIII and Elizabeth executed just as many as Mary did, but over a longer period of time. And they did it for intimidation, in case you hadn’t noticed. And it worked.
If you tote up the scorecard on both sides, it comes out about as equal as you could ever want it to be. It’s not a pretty picture, but don’t start patting your Protestant behind prematurely. Do some actual research. You’ll have to get beyond the textbooks, though. In Anglo-American textbooks, the Protestant bias is palpable and therefore you are not to blame for having gained the impression that only Catholics used violence. But Freepers ought to know a thing or two about how trustworthy the school textbooks are (not).
Once Europeans read the Bible for themselves, they realized that they didn't need hierarchies of priests speaking in dead languages, burning incense, and teaching doctrines which had no basis in the word of God. They learned from the Bible that all men are created equal, that all are valuable, and all are subject to law. Those are the basic principles necessary for free societies. The old rule of wealthy, corrupt church officials and hereditary elites (who were usually just the descendants of bygone warlords) was immediately put at risk.