Since Genesis had unified the whole world, the original Christian era was replaced by a new epoch—the Genestian era.
The year when the virus broke out became the Genestian era's first year. Before doomsday, people would the coming of a new year at the end of the former year. However, for the Genestian era, the last day of the former year was the beginning of the disaster. In other words, celebrating it was equivalent to celebrating death and disaster.
It should be known that 20% or 30% of the world population was lost that day.
Genesis always propagated that the day of the great destruction was actually mankind's Nirvana Day as the weak were eliminated and the strong were reborn.