I've read
this TIA article before (cf.
this thread). There's also
a similar one by an SSPX priest.
I haven't been able to verify that her writings were ever placed on the
Index, although Weigel's JPII biography says they were under suspicion in Rome due to a faulty Italian translation of them.
I do know that the image was banned under John XXIII:
A notification of the Holy Office:
The Supreme Sacred Congregation of the Holy Office, having examined the alleged visions and revelations of Sister Faustina Kowalska of the Institute of Our Lady of Mercy, who died in 1933 near Cracow, has decreed as follows:
1. The distribution of pictures and writings which present the devotion to the Divine Mercy in the forms proposed by this Sister Faustina, should be forbidden;
2. It is left to the prudent discretion of the Bishops to remove such pictures which may have been already exposed for worship.
From the Holy Office, 6 March, 1959.
Ugo O'Flaherty, Notary
(
source of translation)
I used to think the Chaplet was a bit strange in saying that even we laypeople "offer You the Body and Blood, Soul and Divinity of Your dearly beloved Son, Our Lord Jesus Christ…," but the prayer taught by the angel to the Fatima seers is similar in that sense:
My God, I believe, I adore, I hope, and I love You. I ask pardon for those who do not believe, do not adore, do not hope, and do not love You.
Most Holy Trinity, Father, Son and Holy Spirit, I adore You profoundly, and I offer You the Most Precious Body, Blood, Soul and Divinity of Jesus Christ, present in all the tabernacles of the world, in reparation for the outrages, sacrileges and indifferences by which He is offended. And by the infinite merits of His most Sacred Heart and the Immaculate Heart of Mary, I beg the conversion of poor sinners.
The points from her diary of "uniting Myself with you so intimately as with no other creature" and "you will not be judged" certainly could be taken in an heretical sense, and the Host coming from the tabernacle only for her to put it back, thrice, is certainly odd. However,
this Anne Catherine Emmerich passage, e.g., could be interpreted as saying that Pagans, as Pagans, are saved. These are all private revelations, not theological treatises. (See
this for an excellent comparison of the language of spiritual writers compared to that of theologians).
Divine Mercy Sunday was chosen for Low Sunday (a.k.a. Quasimodo Sunday) for very good reasons: the image shows Jesus in his resurrected body after he passed through the door (Gospel); the red and white lights represent the blood and water taken from yesterday's Epistle.
True mercy, which involves calling sinners to repentance, should be celebrated. In Thomist philosopher of science Charles de Koninck's excellent mariological piece
Ego Sapientia: The Wisdom That Is Mary, he quotes, in a section on mercy (PDF pp. 23ff.), Ps. 144:9 (PDF p. 25):
The Lord’s mercies are above all his works.
Miserationes ejus super omnia opera ejus.
and St. Thomas's answer to the question "
Whether mercy is the greatest of the virtues?" (PDF pp. 22-23):
Respondeo dicendum quod aliqua virtus potest esse maxima dupliciter, uno modo, secundum se; alio modo, per comparationem ad habentem. Secundum se quidem misericordia maxima est. Pertinet enim ad misericordiam quod alii effundat; et, quod plus est, quod defectus aliorum sublevet; et hoc est maxime superioris. Unde et misereri ponitur proprium Deo, et in hoc maxime dicitur eius omnipotentia manifestari.
I answer that, A virtue may take precedence of others in two ways: first, in itself; secondly, in comparison with its subject. In itself, mercy takes precedence of other virtues, for it belongs to mercy to be bountiful to others, and, what is more, to succor others in their wants, which pertains chiefly to one who stands above. Hence mercy is accounted as being proper to God: and therein His omnipotence is declared to be chiefly manifested [*Collect, Tenth Sunday after Pentecost].
Sed quoad habentem, misericordia non est maxima, nisi ille qui habet sit maximus, qui nullum supra se habeat, sed omnes sub se. Ei enim qui supra se aliquem habet maius est et melius coniungi superiori quam supplere defectum inferioris. Et ideo quantum ad hominem, qui habet Deum superiorem, caritas, per quam Deo unitur, est potior quam misericordia, per quam defectus proximorum supplet. Sed inter omnes virtutes quae ad proximum pertinent potissima est misericordia, sicut etiam est potioris actus, nam supplere defectum alterius, inquantum huiusmodi, est superioris et melioris.
On the other hand, with regard to its subject, mercy is not the greatest virtue, unless that subject be greater than all others, surpassed by none and excelling all: since for him that has anyone above him it is better to be united to that which is above than to supply the defect of that which is beneath. [*"The quality of mercy is not strained./'Tis mightiest in the mightiest: it becomes/The throned monarch better than his crown." Merchant of Venice, Act IV, Scene i.]. Hence, as regards man, who has God above him, charity which unites him to God, is greater than mercy, whereby he supplies the defects of his neighbor. But of all the virtues which relate to our neighbor, mercy is the greatest, even as its act surpasses all others, since it belongs to one who is higher and better to supply the defect of another, in so far as the latter is deficient.
His piece also contains quotes from St. Albert the Great's
Mariale. St. Albert, St. Thomas's teacher, had a very deep Marian devotion, as he received a vision of Our Blessed Virgin; she deeply transformed him from a man of average intelligence to a genius literally overnight.
From PDF p. 10, a translation from St. Albert's
Mariale:
She is the mother of all things and God the Father is the origin of all things: but whatever is per se the origin and cause of the cause is per se origin and cause of that which is caused. But she is the mother of Him who is the cause and origin of all things: therefore she is per se the mother of all things.
Ipsa est mater omnium, et Deus Pater est origo omnium: quidquid autem per se origo et causa causae est, per se est origo et causa causati: sed ipsa est mater ejus qui est causa et origo omnium: ergo ipsa per se est mater omnium.
Considering St. Albert wrote a lot about causality (cf. e.g.
this), which influenced the development of modern science, his beautiful syllogism carries even more weight.