>>I remember hearing of a bizarre store-front Christmas display in a Japanese store, featuring Santa Claus nailed to a cross.

well, since christmas is a non religious time in japan father christmas finds himself in many strange situations, on top of christmas trees, nailed to crosses (just want to check it wasn't a live one?), but rarely bringing presents or lounging around in shopping centres.
christmas is a time for couples to have dates in japan. it's not a holiday. new year is the religious time you spend with your parents and paying respects at graves.
i guess your shop front was a bit like western people misunderstanding the religious symbols and ceremonies of this country.