Some Christian groups keep them rigidly. Every day ends up a Saint Day. In some countries, every third day is honored somehow. C. Others are addicted to sentimentality. A weakness of Baptists.
Holidays can have a proper place.
The Bible has holy days, especially the Old Testament. New Testament adds Lord's Day, Easter. These are days of special devotion to God. B. Honoring them is optional. Paul says every day is special, because created by God.