Why are church people so ignorant towards other religions but they.....?.?

I am a Christian. I am quite aware that many Christian festivals and observances have roots in pre-Christian cultures. This is not exactly breaking news. I first learned about it in Christian school as a small child. I am hardly ignorant of other religious beliefs; my personal library contains a wide array of non-Christian literature. I have spent many years immersing myself in the study of other beliefs and viewpoints.