As the presence of God radiates outward from His dwelling place in the desert Tabernacle imbuing all of Israel with holiness (if they choose to make themselves receptive to it), the kohanim who perform the service in the Tabernacle are required to zealously guard their special status, and the annual pilgrimage festivals become specially appointed times of holiness near God in His holy house.
Even the non-holy days of the year become essential threads binding the times and seasons together.
The man-inspired innovation of Second Passover is testimony to how much God wants to enable His children to achieve holiness.