Is he right on this?
“Protestants generally misapprehend Catholicism as conservative and never evolving. Instead, it was always capable of radical revisions. For example, on the issue of purgatory, Augustine in the 400’s said there is a heaven and a hell but of a “third place we are entirely ignorant.” Then speculation began in the 600’s on purgatory. It was then only in 1140 A.D. that purgatory became an official doctrine. Then in 1563, it was decreed at Trent that anyone who denied purgatory was cursed and could not be saved. See Isaac Mann, Cursory Remarks, on a Treatise Entitled, Thoughts on Nature and Religion; or, an apology for the Right of Private Judgment, maintained by Michael Servetus, M.D. in his answer to John Calvin by a Clergyman of the Church of England (Cork: William Flyn, 1775) at 24.
As said, I think the objections to V2 have some real warrant, such as expressed by the sedevacantist referred to above.
As for purgatory, thus the EOs generally reject the RC version of it, some more strongly than others, such as Orthodox apologist and author Clark Carlton:
“The Orthodox Church opposes the Roman doctrines of universal papal jurisdiction, papal infallibility, purgatory, and the Immaculate Conception precisely because they are untraditional.” Clark Carlton, THE WAY: What Every Protestant Should Know About the Orthodox Church, 1997, p 135.
The Orthodox Church does not believe in purgatory (a place of purging), that is, the inter-mediate state after death in which the souls of the saved (those who have not received temporal punishment for their sins) are purified of all taint preparatory to entering into Heaven, where every soul is perfect and fit to see God. Also, the Orthodox Church does not believe in indulgences as remissions from purgatoral punishment. Both purgatory and indulgences are inter-corrolated theories, unwitnessed in the Bible or in the Ancient Church, and when they were enforced and applied they brought about evil practices at the expense of the prevailing Truths of the Church. If Almighty God in His merciful loving-kindness changes the dreadful situation of the sinner, it is unknown to the Church of Christ. The Church lived for fifteen hundred years without such a theory. — http://www.goarch.org/ourfaith/ourfaith7076
However, Orthodox churches do believe that,
there is a state beyond death where believers continue to be perfected and led to full “divinization.” Though some Orthodox teachers have described this intermediate state as “purgatory,” others prefer to distinguish it from the Roman Catholic understanding of purgatory, insistingly that it is not necessarily a place of punishment but rather a place of growth....Although Orthodox teachers maintain that such a belief is necessary, there is little speculation as to what it might be like.: — Christian confessions: a historical introduction, by Ted Campbell
The Orthodox Church has neither explicitly recognized the term “purgatory” nor officially accepted such a state, which is distinct from the more general being “asleep in the Lord.” In his book entitled Why Do We Reject Purgatory?, Coptic Pope Shenouda III presents many theological and biblical arguments against Purgatory.
...That said, Greek Orthodox Metropolitan Kallistos Ware acknowledges several schools of thought among the Orthodox on the topic of purification after death. This divergence indicates that the Catholic interpretation of purgatory, more than the concept itself, is what is universally rejected. — http://orthodoxwiki.org/Purgatory
EO descriptions of the afterlife vary, both with the past and among each other, with some being closer to Rome than others, while various claims are made by Catholics, such as “Free 1,000 Souls From Purgatory & they will pray for you unceasingly all your life!”
In the 13th century, Aquinas believed that the pain of Purgatory, both of loss and of sense, surpasses all the pains of this life “(Aquinas T. The Summa Theologica of St. Thomas Aquinas, Appendix I, Article 1.).
And also sated, “Nothing is clearly stated in Scripture about the situation of Purgatory, nor is it possible to offer convincing arguments on this question.” Thomas Aquinas, Summa Theologica, Appendix II (Purgatory), Article 2
Evangelicals see the Scriptures only testifying of believers going to forever with the Lord after death, with purgatory being a later “development of doctrine” (p.109). — http://beggarsallreformation.blogspot.com/2009/02/defending-purgatory-with-all-your-cards.html
It does not sound like the writer fully understands. No Catholic is allowed to dissent on any defined doctrine and remain in the Church. The organization must remain unified to retain the four essential marks of the Church: 1. one, 2. holy, 3. catholic, and 4. apostolic.
Here is the proof text for purgatory:
"Every man's work shall be manifest; for the day of the Lord shall declare it, because it shall be revealed in fire; and the fire shall try every man's work, of what sort it is. If any man's work abide, which he hath built thereupon, he shall receive a reward. If any man's work burn, he shall suffer loss; but he himself shall be saved, yet so as by fire." (1 Cor. 3:13-15)