How important is it to have a knowledge of religion IN TERMS OF cultural education?

In Spain, Italy, Germany and France, there are many many Christian holidays which are celebrated as bank holidays and in some of these countries there are huge festivals and family or social gatherings around such events. I grew up in a household where Christmas and Easter were about the only Christian holidays that were celebrated. As a result, I often feel out of the loop when things are happening around the Pentecost, the Ascension, Good Friday, White Sunday, The Epiphany, Various Saint's Days etc. Should I make it a point to make sure my kids know this stuff or is it not such a big deal?