There is no biblical evidence that Paul or any of the apostles observed Jesus' birthday. There is also no record of any first-century follower of Christ who celebrated His birthday. There is also no mention of Christmas until the 3rd century, and it never gained any popularity until the 4th century.
Up until this time it was never celebrated by Christians, it was only celebrated by pagan druids. It wasn't until the Roman Catholic Church made a blasphemous move and put a supposed birthdate of Christ to match the birthdate of a false pagan druid god. This was one of the first co-exist campaigns.
By the 7th century, Pope Gregory had ordered Augustine of Canterbury to incorporate all pagan practices into the expanding Roman Catholic Church.
In 1223, Saint Francis of Assisi created the first nativity scene in Italy. He wanted the emphasis of Christmas on worshiping Jesus, rather than on materialism and gift exchanges.
However, the Christ-Mass had a "Marti Gras" atmosphere, which is why it gained a LOT of popularity. It was everything, but Christian.
The blood-drenched celebrations got so out of hand in England, the Christ-Mass was finally outlawed in England. Oliver Cromwell and the puritans commanded that Christianity remain pure and separate from paganism.
However, despite their efforts, the Christ-Mass celebrations went underground. By 1656, the public demanded the legalization of the Christ-Mass. When Charles II was appointed, he restored England’s monarchy and the celebration of the Christ-Mass.
The first settlers to the U.S. from England were mostly Puritans. They wanted religious freedom, without a hierarchy and corruption of the organized church. They came over with the knowledge of the danger of these pagan practices.
In 1659, following England’s lead, America had outlawed Christmas. For 200 years, the clergy battled to keep the riotous celebrations honoring the pagan god Saturn from infiltrating the new world.
Reverend Cottonmaker had warned against it in a Christmas day sermon in 1712. But, the public’s taste for sin and revelry had persisted.
In 1828 gang rioting during the Saturnalia-Christmas type celebrations got so bad that cities like NY were forced to issue a professional police force for the first time in order to control the savagery.
Christmas was not widely celebrated and in some places, it was outlawed. This was mainly because many of the churches regarded it a pagan celebration and a reproach to the Lord.
By the mid-19th century, American churches were the last remaining holdout in the war against the validation of Christmas.
However, they also succumbed because of the American Sunday School Society, who began advocating Christmas programs to children as a method of filling the pews. They argued that children could be taught about the birth of Christ through the re-enactment of the nativity. They also offered candy and treats to the kids to entice families to accept the holiday despite its notorious history and blatant pagan roots.
This technique of bribing kids with candy would later be used to promote the acceptance of the pagan rituals of Halloween.
When Charles Dickens wrote "A Christmas Carol" in 1843 it cemented the Christmas holiday into the hearts and minds of American families forever. Dickens’ well-loved story made the pagan Christmas feasts of shiny trees and glittery shops and family warmth irresistible to those wanting to experience the holiday. Coming to America in 1867 to promote his work, Charles Dickens packed theaters as he read his story to America. It stopped any final attempt to stop the evolution of Christmas.
By 1875 the Puritans and all conservative Christians had been beaten. By 1890 all American states had voted in Christmas as a legal holiday.
The following sermon gives a brief historical timeline concerning the rise, fall and rise of the Christ-mass. It also addresses the idea of a Christmas season. https://youtu.be/vYY_sOaw1hc