Yes, it's possible to just do story missions in BL3. But keep in mind that by skipping the side content, you might miss out on additional rewards, lore, and fun challenges.
Angels tell the Christmas story through various ways. In the Bible, an angel appeared to Mary to tell her she would give birth to Jesus. Then, an angel also announced the good news to the shepherds in the fields. They might convey the story with their heavenly voices, full of joy and wonder, and their appearance which is often described as bright and glorious, catching people's attention and making them listen to the important message of the birth of the Savior.
Game elements can enhance BL novels by adding an extra layer of excitement. For example, in a BL novel set in a virtual game world, the battles and challenges within the game can create high - stakes situations for the characters. This makes their relationship more intense as they rely on each other to succeed in the game. The leveling up or obtaining rare items in the game can also be used as symbols of their relationship growth.