Why do most of the events of this poem occur in the context of holiday games?

Despite its Christian message, the poem has strong roots in Celtic pagan myth. There are many elements common to pre-Christian Celtic mythology, such as the waiting period of twelve months and a day, the Beheading Game, and the Temptation Game. The Green Knight himself is a strongly pagan character, similar to the Green Man or Wild Man of the Woods who symbolizes fertility in folklore. Celtic belief is most noticeable in two ways: in the Christmas/New Years setting of the scene and in the figure of the Green Knight. Celtic pagan belief considered the year to be an important cycle in both the human and natural worlds. The Celts designated a certain time of year as the end of the old year and the beginning of the new one. At this "limbo" time of year, strange, supernatural events were likely to happen and the human world was likely to come in contact with the Otherworld of mystical beings