Rev. Prof. Dr. John Calvin (1509-64) was the greatest of all Protestant Reformers. He lived and testified and died — during the time of cruel papal tyranny over the Church of Christ.
There was no Papacy in the Early Church. As predicted in Holy Scripture, it would arise only later — and to test and strengthen True Christians. Daniel chapters 7 to 12; Second Thessalonians chapter 2; First John chapters 2 to 4; Revelation chapters 11 to 18.
This occurred especially from about A.D. 600 onward. It climaxed around A.D. 1215, when the Romish doctrine of transubstantiation was enunciated officially.