데 is a noun that means a place, it doesn't necessarily to be a physical one. So the sentence uses the "에서"(means "from" - "에" is often dropped.) The customs is born from the idea it's supposed to get rid of misfortune and bring fortune.

It simply means "from". you can use it as more flexible form "에서 " 액운이 사라지고 복이 찾아온다고 믿는 것에서 그런한 풍습이 생긴 것이다.