Both can be true. Calvinist philosophy has been blended into most Protestant denominations in the US, particularly concentrated among Evangelicals. Interestingly, the important mechanisms in Calvinism are also being blended into non-Protestant denominations of Christianity here too

John Brown killed enough slavers to get a pass from me on all the other stuff, but he was kind of a hot mess. Vicious at punishing his children, abysmal husband, wanted to replace the US with a slightly-better (i.e. no slavery) theocracy, had a hilarious perspective on Harriett Tubman

He's a fucking hero and I have no doubt at all that his Calvinist beliefs played a role in galvanizing him to action. Unfortunately, it's very rare for it to galvanize people to do anything other than evangelize and ban books