Why is This so Hard?

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Across
  1. 2. Original term for caroling
  2. 7. Old Testament book with many prophesies of Jesus
  3. 12. Name of original elf on shelf
  4. 13. Type of festive holiday log
  5. 14. Center with enormous tree
  6. 15. State letters to Santa go to
  7. 18. Country with biggest light display ever
Down
  1. 1. Years Christmas trees grow before sale
  2. 3. Jingle Bells was first song played here
  3. 4. Original Santa from 4th century
  4. 5. Deck the halls with these
  5. 6. Poisonous Christmas plant
  6. 8. Dutch Santa name
  7. 9. Japan's favorite Christmas meal
  8. 10. Pre-Christian, Roman December holiday
  9. 11. One of the three gifts
  10. 16. Swedes' favorite Christmas duck
  11. 17. WWI had a Christmas ___.