You claim Calvin believed in "the apostasy" but don't back that up. And can't, because quite frankly the Magisterial Reformers didn't believe that the Church had fallen into apostasy and needed to be restored, they believed that errors had crept into the Church--recently--and thus there was need for reform.
Even in your quote you present Calvin as affirming that what he was teaching was, in his view, connected to the historic teachings of the Church--the Creeds, the fathers, and the councils, the very things which have always defined Christian orthodoxy.
-CryptoLutheran
As I am reading this book, I am seeing that this is what the reformers were fighting against:
Total corruption from pope to priest.
Secularized and humanist clergy-meaning many were not even Christian
Clergy that live oppulent, immoral lives, especialy bishops, cardinals and pope
The whole worldly problems that are brought about by money and power, absolute power that corrupts absolutely.
Unlearned, ignorant priests
Arrogant and haughty clergy-the bible says God hates this attitude
Absent Bishops and benefice corruption
Complete state controlled clergy, especially bishops
Murder, and wholesale slaughter and massacre of innocents
Indulgence corruption
Clergy were forbidden to marry-a biblical prophecy about apostasy
Icon worship
Mary adoration and outright worship
The inquisition tortures and outrages
Spying and mischievous and intriguing jesuits against kings & the people
Burning innocents at the stake in the name of Jesus Christ
This History of the Reformation is not just a history of the reformation, it could be renamed the History of the Great Apostasy from 1400 - 1600 ad. The story of an apostasy on a grand scale.
With this list of unconscionable unChristian conduct for centuries upon centuries, is it any wonder that reforming this organization would be impossible?
With this list of unconscionable unChristian conduct for centuries upon centuries, is it any wonder that the doctrinal debates and final conclusions to doctrinal beliefs lead to a changing of doctrines such as baptism, the holy sacrament of the Lords supper, forgiveness of sin, priesthood issues, the nature of God and His Son and the HS, etc., etc., etc.
Calvin wanted to get back to the original church. He could not do it. He did not even come close. If he had come close, his reformer clergy and even his followers would have put him to death.