There have been many other systems of belief that have the messiah rising again on the 3rd day. Christianity is just one and borrows from the previous ones.
Combine this with the belief of the winter solstice being the time of death since many plants have died, animals have undergone hibernation and the sun shines the least. Therefore previous belief systems have the messiah dying on the 22nd of December and rising on the 3rd day which is December 25th.
Combine this with the belief of the winter solstice being the time of death since many plants have died, animals have undergone hibernation and the sun shines the least. Therefore previous belief systems have the messiah dying on the 22nd of December and rising on the 3rd day which is December 25th.