Holidays
Many holidays in America (and elsewhere in the world) are seen as religious and more specifically Christian. But, they have a much more convoluted history than that and are clearly not simply Christian holidays. Many of them have roots in pre-Christian civilization.
Many Atheists and even some Humanists try to abandon many of the supposed Christian holidays or try to establish similar ones that can replace the common ones. This is difficult at best and is often uncomfortable for family and friends as the society in general celebrates these holidays.
Christmas
A court decision in 1990 in Ohio held that Christmas was a worldwide non-religious holiday. The following is a quote about the origins of Christmas in the The Buffalo News in November of 1984:
The earliest reference to Christmas being marked on Dec. 25 comes from the second century after Jesus' birth. It is considered likely the first Christmas celebrations were in reaction to the Roman Saturnalia, a harvest festival that marked the winter solstice - the return of the sun - and honored Saturn, the god of sowing. Saturnalia was a rowdy time, much opposed by the more austere leaders among the still-minority Christian sect. Christmas developed, one scholar says, as a means of replacing worship of the sun with worship of the Son. By 529 A.D., after Christianity had become the official state religion of the Roman Empire, Emperor Justinian made Christmas a civic holiday. The celebration of Christmas reached its peak - some would say its worst moments - in the medieval period when it became a time for conspicuous consumption and unequaled revelry.
The actual Roman holiday was a three day event starting on December 22nd (the winter solstice) and lasting three days. It was said that the sun died on the 22nd and rose again three days later (sound familiar?) on the 25th, which was the climax of the celebration.
So, what about Santa Claus? By some world encyclopedias, "Santa" was a common name for Nimrod throughout Asia Minor. This was also the same fire god who came down the chimneys of the ancient P agans and the same fire god to whom infants were burned and eaten in human sacrifice among those who were once God's people. Today Santa Claus comes from "Saint Nicholas". Washington Irving, in 1809, is responsible for remaking the original old, stern bishop of this same name into the new "jolly St. Nick". Most of the rest of America's Christmas traditions are even more recent than this.
Easter
Easter also has its roots in non-Christian tradition. It is associated with the Spring Equinox and is a time of fertility. The traditions come to us from the Babylonians - Christian priests visited them from Rome in the 6th century and brought back the Pagan ritual; they adapted it to help celebrate the death and resurrection, but many of the Pagan traditions, like egg painting, remained.
Easter is also associated with Passover. It is difficult to tell from historical records, but many believe Passover originated from the same Babylonian fertility rituals.