Much could be said about the specific origins of different holidays, be they pagan or not, but that information can be found elsewhere.
It is important to note that holidays and celebrations were God’s idea, as evidenced by His directives to the people of Israel in the Old Testament. Special days or weeks that He designated were to be times of celebrating His goodness to them, as well as times designed to help His people remember His deliverance and provision. Therefore, holidays per se are neither good nor bad. It depends on what they are for.
For Christians, as per the Church Epistles, there are no prescribed “holidays.” Every day is to be a special day as we live for the Lord. That is not to say that it is wrong to celebrate the birth of Christ, or his Resurrection. Such remembrances can be very meaningful.
“Christmas” definitely has pagan roots, in that late December was originally the time of the Roman festival honoring the Winter Solstice and the pagan gods they worshipped, primarily the Sun God. It was Constantine who proclaimed it the day to celebrate the birth of Christ, and his motives were probably political, and suspect at best.
Jesus was not born in December, but rather in September, as a study of Scripture shows. We have a two hour video that beautifully lays this out called “The Birth of Christ,” and an article called “Was Jesus born on December 25th or early September?”
Does God care if Christians have a Christmas tree, give gifts, etc.? Not at all, as long as we don’t worship the tree. We can remember Jesus Christ and give thanks for his birth and his life. And we can take advantage of the opportunity to talk to people about our Savior and tell them why he was born.
“Easter” comes from the name of the pagan goddess Ashtarte, and relates to fertility and much sexual orientation and debauchery. But at least it comes in the Spring, which is when Jesus got up from the dead. We can call it what we like, maybe “Resurrection Day,” and remember it appropriately. And we can proclaim that the resurrection was God’s proof that Jesus was who he said he was, the Son of God and the only way to everlasting life.
Halloween comes from the ancient pagan festival of Samhain that was practiced by the Celts and is celebrated by today’s neopagans. The Celts believed that from sundown on the last day of the year to sunrise on the first day of the Celtic new year the veil between the land of the living and the land of the dead was at its thinnest, and thus the dead could enter the realm of the living. People wore masks and costumes to ward off the dead or keep them from recognizing the living. The Catholic Church adapted this holiday as All Saints Day, which honors dead people whose souls are supposedly still alive. This spurious idea has opened the door for much of the devilish activity associated with this holiday. Christians should either ignore Halloween or use the occasion to hand out Scripture verses door-to-door, or find some other way to share their faith amidst all the witchcraft, etc. that is promoted in conjunction with this day.