It's nearly 3 in the morning here in Singapore, but I couldn't resist commenting on this thread!
The Maria Kannon is a curious version of the Sino-Japanese school of Buddhism's Guan Yin (Kannon or Kwannon in Japanese) Bodhisattva, also popularly known as the Goddess of Mercy. During the fierce persecution of Catholics in Japan between the 1600s and the 1900s, those secret Catholics would pray before such an image of Kannon, specifically the version where she holds a book in one hand and a boy child in another. This is traditionally what the Chinese call 'Guan Yin - the giver of sons'. These Catholics would, in their hearts, see it as an image of the Mother of God.
Of course, this is one of those ways in which history plays ironical tricks on us, for the whole image of a caring, motherly, female figure, is totally absent from the original Indian school of Buddhism.
In a nutshell, without bothering you all with the details, when Persian Christianity entered Tang China in the 7th and 9th Centuries, the Buddhists found that the Christians with their concept of the Mother of Christ (Nestorians/Assyrians after all) had an advantage over them. Ergo, they changed the gender of a particular Buddhist saint/Bodhisattva from male to female and ascribed those qualities that we usually associate with the Mother of God to this new deity. The very name Guan Yin means, literally, 'noticing sounds', but more idiomatically it means 'the one who listens' or 'hearer of cries' - I don't know about you, but that strikes me as being suspiciously similar to a certain icon of the Mother of God, called the Gorgo-ypeko÷s, or 'quick to hear'.
We know that the Buddhists changed the gender of this deity in the 9th century - it's mentioned in a number of Chinese historical and religious texts of the period. One odd detail is that knowledgeable Chinese Buddhists know this, and their explanation is that the Guan Yin changed her image from male to female to make the message of Buddha more appealing to the masses, and that this change is only external. In other words, to put it crudely, Guan Yin is something of a drag queen.
At any rate, my point being that since the whole Buddhist Guan Yin/Kannon Bodhisattva image is derived from Christian influence in China, reclaiming that image for Christian purposes is strangely appropriate.
How's that for things coming full circle?