Ok, for starters the puritans did not want freedom of religion. They wanted freedom from the church of england and freedom from outside influence. Once here, they set up a theocracy, which banned free practice, set up laws where lack of church attendance was a crime, and the church was the government. At a conservative christian college I was taught that much. In high school, they tend to skip over those parts. Yes, I will give say that the first Thanksgiving was giving thanks to god for making it through the year. However, it has since became an American holiday, observed nationally by Christians, Jews, Muslims, Hindus, and Atheists alike. I wasn't aware (not saying it isn't the case) that churches themselves observed Thanksgiving as a religious holiday. I mean, Christmas is a Christian holiday, but I still celebrate and enjoy this time with my family and friends as a secular occasion.
God isn't out of public schools. Most PUBLIC schools around here have at least Young Life and the Fellowship of Christian Athletes. The Christian word just can't be taught in the context of worship. Passages from the bible were read in both my high school history class and my high school English class. And students were free to bring their religious texts and read them, or pray during noninstructional time. I don't see how that is kicking God and religion to the curb.
I don't say "under God" in the pledge, however I think it is silly that it be banned. If people want to, it doesn't hurt me or affect my learning, so more power to them.