Christmas pagan beliefs are usually traced back to the ancient Roman celebration of Saturnalia. Saturnalia was a celebration that usually started on December 17 and for many years lasted a full 7 days long ending on December 23. This was during the winter season when there was not as much responsibility throughout the community and there was not so much harvesting of crops because the winter was not normally a growing season so this was when the ancient Romans would celebrate the commemoration of the temple of the god Saturn which they attributed to December 17. This was the most important public holiday throughout all of Italy and it was a cause for government offices to be closed and public schools to be closed as well. All of the citizens would give small gifts to each other and slaves were even allowed to feast as well. Sound familiar yet? This is where it gets very Roman. Saturnalia was also a time for drunken celebration all week long, great feasting, and public nudity and orgies. The slaves were not only allowed to celebrate but it went so far as to allow slaves to treat their masters like slaves and one of the feasts the slaves would have would be served by their masters. It was a joyous time and it was anticipated greatly each and every year.
The Romans also celebrated a holiday they call Sol Invictus and this fell right on December 25. As the Christians began to become more prominent in the Roman society they changed Sol Invictus to Christmas and replaced the Sun God with Jesus in order to try and convert the Romans to Christianity. Soon the December 25 holiday had replaced Saturnalia but many of the Saturnalia traditions and celebrations were used during Sol Invictus and were continued when Sol Invictus was changed to Christmas. Christian scholars can never really agree if the Christmas pagan beliefs really were the origin of our modern Christmas celebration but it certainly looks like much of what we do today had its origins in ancient Roman pagan celebrations and the attempt by Christianity to make those celebrations their own in an attempt to convert Romans to Christianity.