It wasn't that she hated Christmas. Not really. She didn't have anything against the concept of Christmas. It was just the execution of it that pissed her off. Why people needed a day set aside when they would all lie about how much they liked each other was beyond her. Worse yet, there were gifting obligations involved.
It wasn't like it was someone's birthday. With that there was always the option to pretend that you forgot the date and very few people were pushy enough to remind her ahead of time. But Christmas? Christmas was everywhere. No pretending that you forgot that. It was absolutely ridiculous to have the day so hyped that you couldn't even ipretend/i that you forgot about it.
Mary firmly believed that Jesus would be on her side with this issue.