Two Main Christian Holidays, which are now pretty secular
Christmas and Easter
Easter has pagan roots, which you can read about on the internet, but this holiday is not really associated with paganism anymore in its current practice. It is positive in terms of celebrating Spring -- colorful chicken eggs, little baby bunnies, green grass, Easter egg hunts, baskets full of treats or gifts, and a delightful family meal (the ham or pork roast is nonkosher though). Seems kind of harmless on the surface, except that it has in many homes, replaced the religious and spiritual observance of Christ's resurrection, depending on the family's or church's observance. Commercialized Easter is the big distraction.
Also, the date was changed from its true observance. It was always supposed to be in conjunction with Passover just 3 days before. Christ died on the evening observance of Nisan 14, at the Spring Passover. He rose on First Fruits on the 17th of Nisan. He was the first to be resurrected from the grave. See 1 Corinthians 15:20. Good Friday, being only a day and a half away from Easter morning, is another reason why the Jews find contraindications in Christianity. They are looking for things to line up on their criteria list. If the Gentiles are in error in so many ways, why should they look even further?
The Early Church disliked the Jews and so they came up with their own method for determining Easter's date. Easter is sometimes referred to a Pascua, or Pascal Lamb. Passover is called Pesach in Hebrew (ch almost sounds like a "k" sound). Other European languages also call Easter a version of Pascua, showing that Easter was originally part of the Passover week!!! You can go to https://translate.google.com or any other language translator that you have and see for yourself.
The religious observation of Easter should be moved to First Fruits on Nisan 17 during Passover week, if things are going to be done the right way. If one must keep Easter when the world celebrates it, consider leaving it as a Seasonal holiday celebrating Spring itself and the gift that God gives us every year of the earth's renewal, if you wish. Some people quit the usual Easter all together and celebrate it only in conjunction with the Passover week, as Resurrection Day.
Others might move the whole holiday to the Hebrew date.
Christmas also has pagan roots, just like Easter does. It was a Winter Solstice holiday. During this season, the pagans celebrated Saturnalia and Sol Invictus. Aspects of these two festivals were merged and cleaned up by Christianity. You can read about these festivals on the internet.
The main problem with current Christmas, is that it has become super commercialized with billions of dollars worldwide going to the merchants. It also isn't a happy time for everyone due to poverty, illness, family problems, work problems, shopping, traffic jams, and party stress, etc, with some people being desperately left out. Many people go into months of debt just to uphold the holiday's expectations.
Then again, for us Northern Hemisphere people, there's nothing like the pretty lights, decorations, the smell of pine, and the freshly fallen snow and the fine food. Also, at this time, so people do great acts of kindness for others, and visit loved ones. The seasonal and religious music is beautiful. The scriptures do not record December 25th as Jesus' birthday and some people already realize this. Hundreds of years of customs are built up around this holiday observance, it's hard to undo a cultural celebration. As a minimum, church leaders ask people to not overdo it during Christmas, and to remember not just Christ but also somebody else in need. Some Mormons do somehow recognize Jesus/Yeshua on April 6th. We would be interested in hearing how it is observed.
Some people think that the prophet Jeremiah was condemning the future observance of Christmas. You can check it out for yourself in the Bible: Jeremiah 10: 2-5.
Mormon teachings show that the formation of the Church on Tuesday, April 6, 1830, was supposed to honor the birth of the Lord. (D&C 20). According to www.hebcal.com, April 6, 1830 was the daylight hours before the first Passover evening. There are some different opinions about when Jesus/Yeshua was born, and it's just too complicated to comment on that, at this time. Jesus was born when it was lambing season, which is typically Spring.
Also, Jesus did go to the temple at Passover when he was 12 and talked with the teachers and elders. This seems to suggest a Spring birthday because custom is to have the Bar Mitzvah on one's Hebrew birthday or near that date. Maybe boys' Bar Mitzvahs were at age 12 back then.