MH: If playing cards and Tarot cards were invented solely for gaming, though, and were not originally used for divination or for any other higher purpose, it’s curious that the suits chosen for the cards would be so spiritually and mystically significant, and that the number of cards in a Tarot deck would have so many echoes in magical culture. We must consider, too, that in the 7th century, iconoclastic Christians waged an extensive campaign to destroy what was likely an enormous amount of Pagan cultural artifacts and documents that they found offensive. So, a lack of evidence may not necessarily be taken as absolute proof against an earlier origin of the Tarot. But it definitely doesn’t prove there was one, either, of course.
You mentioned that the Tarot's imagery is based on Christian themes. Some people believe that the Tarot was intended to preserve Pagan spiritual teachings in a disguised form that wouldn't be understood for what it was by non-initiates. Taking into account the Hanged Man, and the World card’s goddess, which seem to not have any “matches” in original Christian ideology, and also the fact that the Christian church was traditionally unfavorable to cards, and to the idea of providing "spiritual reading" material to illiterate people and lower class citizens, do you see a case for the cards being "surface Christian," and more deeply Pagan, in origin and ideology?
MKG: Throughout Italy there is an interesting mix of Christian and Pagan imagery (i.e., Greek and Roman myths) that is surprising to Americans. Yet, there's no evidence of the Tarot having Pagan or pre-Christian roots other than those at the base of all of Western knowledge.
The Hanged Man was a common image used to depict debtors and traitors in the 15th century. Several of these 15th century "shame paintings" survive, most notably those by Andrea del Sarto. In fact, at the end of WWII, Mussolini was hung upside down to deliberately mark him as a traitor.
The World card can be seen in many churches and manuscripts, usually showing a part-naked Christ with winding cloth ascending into heaven surrounded by symbols of the four evangelists and gospels (the tetramorphs). Occasionally Mary or Sophia (Wisdom) is depicted similarly. The earliest Tarot cards showed an angel surmounting a globe on which there is a walled city. This is a common image for the "New Jerusalem"—the kingdom that will come.
A search through the Historical Research board at Aeclectic Tarot's forum will turn up dozens of historical images from Italian 14th and 15th century art that parallels each of the Trumps.