Calvinism is simply another name for biblical Christianity. Sadly, the Roman Church hid the faith from sinners for centuries. It took men like Wycliffe, Hus, Luther and Calvin to recover the gospel. By the time they came along so few understood what Christianity is and what it looks like movements developed in their name. But, make no mistake, Calvinism is Christianity. God is sovereign in all things, including the salvation of sinners.
I don’t see Calvin in the Bible. Or Luther. Or any of the Protestant revolutionaries.
What teaching authority did they have?
Calvinism is nothing more than a cult.