This was the belief in the Danish Lutheran church that they were the chosen ones and can treat anyone else like garbage, much like orthodox Judaism. This was the variant of Lutheranism used to justify imperialism in Greenland and treating the Inuits like trash. Calvinism is evil, and its biggest manifestation was in Danish Lutheranism.
Calvinism (also called the Reformed tradition or the Reformed faith) is a major branch of Protestantism that follows the theological tradition and forms of Christian practice of John Calvin and other Reformation-era theologians. Calvinists broke with the Roman Catholic Church but differed with Lutherans on the real presence of Christ in the Lord's Supper, theories of worship, and the use of God's law for believers, among other things.
Hence to the extreme it goes to be an evil and insanity in the context of humans.
It's incoherent to call something inherently evil. On the Calvinist view, 'good' and 'evil' aren't substantive concepts, so it's meaningless to predicate something with goodness or evilness. There don't seem to be any coherent views of stuff like 'good' and 'evil', so it's hard to understand what it would even mean to say that Calvinism is evil, let alone 'inherently' evil.