According to the Catholic Church, Maria Valtorta's writings are permissible for publication, reading, and promoting. They leave it up to each individual to decide if it's of supernatural origin and for their spiritual benefit or not.
That's not quite the whole story ...
The book was placed on the Index of banned books, and when the index was lifted, that did not give the OK for publication. Morally, as then Cardinal Ratzinger (Pope Benedict) said (in
L'Osservatore Romano June 15, 1966): "The Index retains its moral force despite its dissolution."
Further comment followed:
"The 'visions' and 'dictations' referred to in the work, "
The Poem of the Man-God" are simply the literary forms used by the author to narrate in her own way the life of Jesus. They cannot be considered supernatural in origin."
The best that can be said for "The Poem of the Man-God" is that it is a bad novel. This was summed up in the L'Osservatore Romano headline, which called the book "A Badly Fictionalized Life of Jesus."
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A brief look on the web and I found this, a critique in
The Catholic World Report by the medievalist Sandra Miesel
“A monument to pseudo-religiosity”: A case against The Poem of the Man-God
The Poem’s fundamental flaw is its claim to compensate for the inadequacies of the Gospels. As Jesus himself explains to Valtorta, the New Testament needs to be supplemented (I: p. 432) because of the evangelists’ “unbreakable Jewish frame of mind.” Their “flowery and pompous” Hebrew style kept them from writing everything that God wished. (V: p. 947) So nineteen centuries later, he finds a worthy secretary in Valtorta, his “Little John,” to expand what the Apostle St. John and the others wrote. “There is nothing of my own in this work,” she insists. (I: p. 57) She presents herself as a mere transmitter of Divine content.
But Hebrew is no “flowery” language. Neither is the simple and concrete koine Greek, in which at least three of the Gospels were composed. Moreover, the evangelist Luke was Greek, not Jewish. Nevertheless, Jesus denounces future critics of the Poem who dare to search for mistakes “in this work of divine bounty.” (V: pp. 751-52) The Poem is self-authenticating and any discrepancies were put in it by Jesus himself. (V: p. 753)
Valtorta’s own prose, however, is flowery in the extreme. Consider her page long description of newborn baby Mary (I: p. 24-25) wherein her fists “are two rose buds that split the green of their sepals and show their silk within.” Her figures of speech monotonously feature flowers, jewels, and fabric. The literary effect is further hampered by her fondness for exotic words (“noctules” for bats) and translators’ clumsiness (a line of laden donkeys is rendered as an “asinine cavalcade.”)
The Poem also presumes to “correct” the received text of Scripture. Valtorta’s reading of John 2:4 adds a novel “still” to Christ’s remark concerning the wine at Cana: thereby making it a comment on their own relationship: “Woman, what is there still between me and you?” (I: pp. 283-84) But her reading has no basis in the Vulgate or in any translation into a modern vernacular from the original Greek. The Poem presumes to place itself above the Bible and “Little John” beyond criticism.
Despite claiming a purely celestial origin, the Poem somehow incorporates legendary material from the Apocrypha (ex.” The Acts of St. Paul and Thecla), The Golden Legend, The Meditations of Pseudo-Bonaventure, the revelations of St. Birgitta, and other medieval texts. (Is she borrowing from Carmen when Mary Magdalen tries to attract Jesus’ notice by throwing a rose at him?) Valtorta is at odds with the revelations of Maria de Agreda and Bl. Anne Catherine Emmerich in chronology, familial relationships, and details of key events such as the Passion and Assumption. For instance, in the Poem Mary lives and dies in Jerusalem, not Ephesus as the other two visionaries say. The personal stories of the Apostles, however, aren’t traditional. Peter is a short, middle-aged buffoon; Simon is an actual “Canaanite” and not Jesus’ cousin. Judas gets far more coverage than all the other Apostles put together.
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Valtorta's Holy Land is a 'flower-strewn fantasy world', what little she knows about first century Palestine and Jerusalem – and clearly, it seems, she knows little – could have come from maps and study aids commonly bound in Catholic Bibles.
Her landscapes, sets, props, and costuming recall soft, gilt-touched Italian holy cards. She is amazingly ignorant of the local living conditions. Her houses resemble Italian farmhouses with fireplaces, porches, and kitchen gardens. The rich enjoy jasmine pergolas and hedged gardens closed with iron gates. The countryside abounds with apple orchards. fields of rye, stands of cactus and agave. Apples are ubiquitous. Dates, figs, and olives seldom appear; lentils, chickpeas, or onions never. People routinely drink fresh milk, even honey-water and cider, but wine scarcely ever appears. The screwdriver and the iron horseshoe are in use, although they were unknown in ancient Palestine.
Valtorta acknowledges her confusion about the layout of the Temple, but still erroneously pictures it as having multiple gilded domes, angel-headed capitals, and a choir of maidens. Not only does Jesus have a bar mitzvah, a ceremony which didn’t yet exist, everything described is false, even to the name of the Bible book he reads as a “test” administered by a bored Temple functionary. Although speaking the Divine Name was taboo, Jesus himself says “Yaweh. “Jehovah”, a word unknown in antiquity, is freely used by other speakers, including Mary and Peter.
But Valtorta’s anachronisms are not nearly as objectionable as her distorted characterizations of Jesus and Mary. They are, of course, fair-haired, blue-eyed, alabaster-skinned and straight-nosed, quite unlike the swarthy Jews around them. A pale complexion—usually but not necessarily—signifies great holiness. (Note that Mary Magdalene and girlish John are fair while Judas is dark.) A hooked nose, however, is always an ominous feature.
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This is just the start of a thorough critique by someone who has read the entire corpus.