Against Isaac the Syrian

Isaac the Syrian, also know as Isaac of Nineveh, was a 7th Century bishop of Niveveh from Qatar who was almost certainly a member of the Church of the East, yet he is considered a saint by the Orthodox Church and some eastern Catholic Churches, though not recognized in the Roman church. 

Bishop Barron has cited Isaac the Syrian for his contention of the possibility of an empty Hell, however Isaac treated Hell more like a purgatory where many people went to for a time. Isaac's 'hope' was an expectation and not limited to human, but included Satan himself. In addition, several Orthodox memes quote Isaac on Hell, often omitting the fact he denied it's unending nature.

The following include excerpts of the Russian Orthodox bishop, Metropolitan Hilarion Alfeyev's book, "The Spiritual World Of Isaac The Syrian" (2016)

Concerning Isaac's church--the Church of the East, Metropolitan Alfeyev writes:

"A local council in 585 confirmed the unshakeable authority of Theodore and forbad anyone 'in open or in secret to defame this Doctor of the Church or to refute his holy books" Subsequently two other Councils, in 596 and 605, condemned Henana's interpretations and repeated the anathemas against those who 'refute the commentaries, exegeses and teachings of the proven teacher, the blessed Theodore the Interpreter, and who attempt to introduce new and strange exegeses replete with folly and blasphemy'. The faith of the Church of Persia became 'the faith of Theodore', or 'of Theodore and Diodore', --The Spiritual World of Isaac The Syrian. Hilarion Alfeyev. 2016 

Notice the phrase "blessed Theodore the Interpreter"? Isaac used that exact phrase when quoting him on universal reconciliation! Diodore of Tarsus, though considered a saint in the early Church was a universalist in all likelihood.  Isaac's communion openly made Theodore of Mopsuestia their standard and doctor of the church. Nestorius got Nestorianism largely from Theodore of Mopsuestia. Theodore rejected theotokos too, he believed Mary was anthropotokos and only indirectly theotokos.

Metropolitan Hilarion writes:

"By the mid-seventh century the names of 'the three teachers'--Diodore, Theodore, and Nestorius--were inserted in the diptychs of the Church of the East and they were commemorated ever since."

"The Church of the East continued to commemorate Theodore and Diodore after they had been anathematized in Byzantium, and it included the name of Nestorius on the diptychs long after he had been condemned. All of this testifies that the Church of Persia, though not 'Nestorian' in a strict theological sense, adhered to the theological and Christological thought which was rather close to that of Nestorius."--The Spiritual World of Isaac The Syrian. Hilarion Alfeyev. 2016 

So, clearly the Church of Isaac the Syrian was fairly close theologically to Nestorius himself, and considered him a saint along with his teacher--Theodore of Mopsuestia. 

Isaac the Syrian,  held the writings of Theodore of Mopsuestia in high regard, as indicated in the following:

"anyone who likes can turn to the writings of the blessed Interpreter, a man who had his sufficient fill of the gift of grace, who was entrusted with the hidden mysteries of the scriptures, (enabling him) to instruct on the path to truth the whole community of the Church; who, above all, has illumined us orientals with wisdom -- nor is our mind's vision capable enough (to bear) the brilliancy of his compositions, inspired by the divine Spirit.... From the blessed Theodore, the Interpreter. After other luminous statements he says...."--Homélies Ascétiques, Isaac of Nineveh (Isaac the Syrian), The Second Part, Chapter IV-XLI. Translated by Sebastian Brock. (emphasis mine)

Some Orthodox apologists claim "The Second Part" is not Isaac the Syrian at all, but some other heretic, or possibly even another Isaac mistaken for their St Isaac the Syrian. However, even if we take Isaac's writings before the rediscovery of "The Second Part" it is evident Isaac was a heretic, some universalists suggested Isaac was one of them by Isaac's statements about Hell, though not as explicit as "The Second Part" we have now.  In the first part, Isaac still quoted Theodore of Mopsuestia calling him the "blessed Interpreter" there too:

"Concerning all these things one may be well instructed in particulars from the writings of the blessed bishop Theodore, the light of the whole world. For he speaks about the kind and the rank of revelations, especially in the three volumes on Genesis and in the two volumes on Job and in the last one about the Twelves Prophets, and in the commentaries on the Acts and the Gospel of Matthew."--Isaac of Nineveh, Mystic Treatise, XIX, On the Revelations and Powers which Happens to the Saints in Images. Page 105-106

"...as the blessed commentator denotes in his commentary on the story in the Acts: And those who went on the way with Paul...."--Isaac of Nineveh, Mystic Treatise, XIX, On the Revelations and Powers which Happens to the Saints in Images. Page 106

"The is clearly proved by the blessed commentator in the second volume on Job.--Isaac of Nineveh, Mystic Treatise, XIX, On the Revelations and Powers which Happens to the Saints in Images. Page 108

Concerning the condemnation of Theodore of Mopsuestia, whereas Isaac the Syrian stated he was "blessed", "illumined", etc. the ecumenical council stated strongly for the contrary:

First, we considered Theodore of Mopsuestia. When all the blasphemies in his works were exposed, we were astonished at God's patience, that the tongue and mind which had formed such blasphemies were not straightaway burned up by divine fire. We would not even have allowed the official reader of these blasphemies to continue, such was our fear of the anger of God at even a rehearsal of them (since each blasphemy was worse than the one before in the extent of its heresy and shook to their foundation the minds of their listeners), if it had not been the case that those who revelled in these blasphemies seemed to us to require the humiliation which their exposure would bring upon them. All of us, angered by the blasphemies against God, burst into attacks and anathemas against Theodore, during and after the reading, as if he had been living and present there. We said: Lord, be favourable to us; not even the demons themselves have dared to speak such things against you. --The Second Council of Constantinople, Sentence against the "Three Chapters" AD 553

The voluminous amount of contempt for Theodore of Mopsuestia is too much to quote! But the council stated he is anathema:

Consequently we anathematize the aforesaid three chapters, that is, the heretical Theodore of Mopsuestia along with his detestable writings,--The Second Council of Constantinople, Sentence against the "Three Chapters" AD 553

Initially, the Pope, while recognizing Theodore as having heretical theology, was hesitant to anathematize someone long after death, eventually he went along with it.

Bishop Alfeyev mentions Isaac depended on Evagrius:

"According to Brock, Isaac's style--phraseology and terminology--"owes a great debt to two writer in particular, John the Solitary and Evagrius'.....Isaac mentions Evagrius by name and many times quotes from him"--The Spiritual World of Isaac The Syrian. Hilarion Alfeyev. 2016

Issac calling Evagrius (Euagrius)"the sage among the saints", "blessed". A few instances include:

"And the following word has been said by the sage among the saints, Mar Euagrius, who did every thing which he did with a purpose: Prayer is a joy that gives place to thanksgivings."--Isaac of Nineveh, Mystic Treatise, VIII: What it is that helps a man to come near etc. Page 72

"The blessed Euagrius has well said: A clear way is founded upon mercy."--Isaac of Nineveh, Mystic Treatise, LXII: On True Knowledge and Temptations etc. Page 306

"And also the blessed Euagrius witnessing to this through real experience, has committed it to writing, for the sake of ampler confirmation, as it were lest any one should think that the blessed Macarius wrote this in his letter fortuitously without having examined his words carefully..."--Isaac of Nineveh, Mystic Treatise, LXII: On True Knowledge and Temptations etc. Page 333

"As also the blessed Euagrius says: the mind which by the grace of God performs works of excellence and approaches unto knowledge, perceives little of the foolish part of the soul."--Isaac of Nineveh, Mystic Treatises. LXXIV: On the Discrimination of Virtues etc. Page 345 

Yet, according to the third Council of Constantinople in AD 680-681, the prior council Constantinople ecumenical council (AD 553) was in part to condemn Evagrius:

Wherefore this holy and universal synod of ours, driving afar the error of impiety which endured for some time even till the present, following without deviation in a straight path after the holy and accepted fathers, has piously accorded in all things with the five holy and universal synods: that is to say, with...... 5. the fifth holy synod, the latest of them, which was gathered here against Theodore of Mopsuestia, Origen, Didymus and Evagrius, and the writings of Theodoret against the twelve chapters of the renowned Cyril, and the letter said to have been written by Ibas to Mari the Persian.--Third Council of Constantinople. Exposition of Faith. A.D. 680-681 (emphasis mine)

The bishop explains how the Orthodox church came to recognize his as a saint---it happened hundreds of years later:

"by the eleventh century, the Greek translations of his writings made Isaac widely known in the Greek-speaking East; in the famous anthology of ascetical texts, the Evergetinon, passages from 'abba Isaac the Syrian' stand on the same footing as those of classics of early Byzantine spirituality. This is how a modest 'Nestorian' bishop from a remote province of Persia became a Holy Father of the Orthodox Church of Chalcedonian orientation...."--The Spiritual World Of Isaac The Syrian. Hilarion Alfeyev. 2016

How can you conclude from Metropolitan Hilarion's book, and from Isaac's veneration of Theodore of Mopsuestia and Evagrius that Isaac was orthodox?

The most perplexing thing about the canonization by some of Isaac the Syrian is his veneration of formerly condemned heretics and doctrine at a time after an ecumenical council ruled against the heretics and their heresies. Ironically, those condemned by Constantinople II were condemned after death as heretics though in life being presumed to die within the Church, while Isaac the Syrian was on the opposite end and venerated, being known only hundreds of years after death, despite his heresy and rejection of an ecumenical councils rulings. 

Isaac the Syrian taught even the restoration of the demons:

And it is clear that He does not abandon them the moment they fall, and that demons will not remain in their demonic state, and sinners will not remain in their sins; rather, He is going to bring them to a single equal state of completion in relationship to His own Being in a state in which the holy angels are now, in perfection of love and a passionless mind--Isaac the Syrian, The Second Part, Chapter 40:4, translated by Sebastian Brock

This doctrine was anathematized explicitly in AD 543 by Pope Vigilius, Eastern Patriarchs and Emperor Justinian:

Can. 9. If anyone says or holds that the punishment of the demons and of impious men is temporary, and that it will have an end at some time, that is to say, there will be a complete restoration of the demons or of impious men, let him be anathema.--Book against Origen of the Emperor Justinian, AD 543 (Denzinger 211)

How is such a blatant heretic a saint? How can bishops such as Robert Barron cite Isaac the Syrian as a legitimate source? The Second Council of Constantinople, contrary to what is commonly believed, seemed to suggest the heretics anathematized post humously by it, including Theodore of Mopsuestia and Evagrius died "separated from God" in other words.....damned to Hell.

Addedum: This link contains an Eastern Orthodox defense of Isaac, from a mystical albeit non-academia point of view.mystical albeit non-academic point of view.