Calvinism was a very important theoretical development in Christianity and western religion and western philosophy. It's really solidified the belief that good things happen to people because god loves them and bad things happen to people because they're sinners. Before that the dominating view was that everyone was a sinner together. Calvinism is fundamental to the development of Capitalism because it's when the predominant religious and philosophical belief came to be "Fuck you poors I got mine because god loved me". Wealth was no longer seen as a bad thing but in fact viewed as proof that you were literally chosen by god. And since you were chosen by god anything you did was by definition righteous, and your continued accumulation of wealth was proof. Not to say Europe didn't exploit a whole lot of horrors before Calvinism, but Calvinism was none the less a key change in how European society thought and functioned.