This is an excellent question!
For those who have never heard of her, Mrs. Vassula Ryden, a Greek Orthodox residing in Switzerland, disseminated 10 – 12 volumes of messages that she believes are from Jesus Christ. The messages promote devotion to the Sacred Heart of Jesus and the Immaculate Heart of Mary, the need for the sacraments, conversion, fidelity to the Pope, and encourage the Orthodox Church to unite with Rome. Followers of Ryden claim thousands of conversions and even some (undocumented) miracles attributable to these messages.
But there are very real problems with these messages, not least of which is how they were received. This is how Mrs. Ryden explains the process:
“I was making a list of expenses for a new cocktail party the same evening. At that moment I had this sheet of paper and I was writing what I had to buy for the afternoon. While I placed my hand with the pencil on the paper, all of a sudden I felt throughout my whole body some electricity that was coming into me through my fingers and especially on my right hand. Everything I held seemed like it was glued. The pencil no longer detached itself from my fingers. Even if I wanted to get rid of it, I could not lift it up anymore, I could not open my hand anymore. And the sheet of paper became like a magnet again. As if my hand was glued, I could not lift it anymore, as if my hand weighed 100 kilos, I could no longer lift it. All of a sudden an invisible force pushed my hand. I was not afraid, I do not know why. I relaxed my hand to see what would happen, and some words came, it was no longer my writing, and they said: “I am your angel [...]. My name is Dan (Daniel.”
Daniel was later replaced by Jesus, God the Father, the Virgin Mary, and various other saints.
As Father Francois-Marie Dermine O.P. explains in this article on the Catholic Culture website, Mrs. Ryden at first experienced the phenomenon of the hand that was forced, almost against her will, to write. She later began to hear interior locutions that she would write down without her controlling it.
“These modes of transmitting messages are and remain typical of the forms of mediumship (medium activity) present both in spiritistic circles, often disguised as ‘prayer groups’ that make the claim of communications with the afterlife, and in neo-spiritistic New Age circles where they speak of channeling or communicating with ‘higher’ spirits.”
Although her supporters referred to this writing as “hieractic”, “inspired”, or “guided”, these descriptions fit perfectly with the definition of automatic writing that was offered to Father Dermine by a New Age representative who described it as writing that takes place “without conscious control, the source of which apparently is not the person who is writing.”
Some supporters have tried to explain the phenomenon by comparing it to the suspension of faculties that sometimes occurred to saints when they were in ecstacy. However, “that has nothing in common with the phenomenon of Vassula Ryden’s writing,” Father Dermine writes. The saints did not experience a force or a paralysis imposed on their faculties or members from outside. Instead, "the suspension of the faculties here comes from an intense absorption of the consciousness or of the mind in things divine.”
There are other reasons why the means with which these writings were obtained is suspect, namely that they contain several serious doctrinal errors.
“Among other things, ambiguous language is used in speaking of the Persons of the Holy Trinity, to the point of confusing the specific names and functions of the Divine Persons,” says a report from L’Osservatore Romano, the newspaper of the Vatican. “These alleged revelations predict an imminent period when the Antichrist will prevail in the Church. In millenarian style, it is prophesied that God is going to make a final glorious intervention which will initiate on earth, even before Christ's definitive coming, an era of peace and universal prosperity. Furthermore, the proximate arrival is foretold of a Church which would be a kind of pan-Christian community, contrary to Catholic doctrine.”
Also, after some of these errors were pointed out to Mrs. Ryden, they disappeared from the messages.
“The fact that the aforementioned errors no longer appear in Ryden's later writings is a sign that the alleged ‘heavenly messages’ are merely the result of private meditations," the report continues.
She was also in the habit of attending the sacraments of the Catholic Church even though she is Greek Orthodox. “Mrs. Ryden is causing considerable surprise in various circles of the Catholic Church," the report states. "She appears to be putting herself above all ecclesiastical jurisdiction and every canonical norm, and in effect, is creating an ecumenical disorder that irritates many authorities, ministers and faithful of her own Church, as she puts herself outside the ecclesiastical discipline of the latter.”
For all of the above reasons, in 1995, in spite of some of the positive aspects of her writings, the Congregation for the Doctrine of the Faith requested the intervention of the Bishops to inform the faithful of these problems and allow no further dissemination of her ideas.
“Lastly, the Congregation invites all the faithful not to regard Mrs. Vassula Ryden's writings and speeches as supernatural and to preserve the purity of the faith that the Lord has entrusted to the Church.”
Some have said that people can read Mrs. Ryden’s works because the Church never officially condemned them, but the only reason this did not happen is because she is a member of the Greek Orthodox Church which is not under the jurisdiction of the Catholic Church.
As our blog on the subject reported in 2013, readers should also be warned that Ryden’s website displays a letter allegedly written by then-Cardinal Joseph Ratzinger in 2004 saying that participation in her ecumenical prayer groups should be left up to diocesan bishops. However, Cardinal William Levada, prefect for the Congregation for the Doctrine of Faith confirmed as recently as 2007 that the 1995 notification against Ryden was still in effect.