There are other beliefs besides Christianity.
I grew up in New England in the 1960's where life was very conservative, and Christianity was the religion of choice. In fact, I knew one Jewish family and as a Protestant, the only other religion I knew about was Catholicism. That was THEN. In school we prayed, and until Madelyn Murray O'Hair railed against the school prayer issue, we thought nothing of it. Out life was homoganized, pure white, wholesome and not reality.
Living in a global world, we now know there are many other spiritual beliefs in the world, including no belief. We are told we have the freedom to practice any of these beliefs, or not and we pretty much stay with our original religion due to our upbringing and our propensity not to seek change.
When I was in my mid forties, my world opened up and I became aware of different religions, spiritual beliefs and philosophies. I also became more aware of the biases inherent in them, and in particular saw how Christianity was deemed to be the "better choice". I grew up celebrating Christmas, Easter and other holidays without thinking too much about it. Of course, I knew the spiritual background of the birth, teaching, death and resurrection of the Christed one, but I also found the story to be more allegory, and symbolic in nature. The things we bring into the holidays are all based on pagan themes. Trees, bunnies and the like are all Celtic in origin. Jesus did not have anything to do with this stuff.
Recently, I learned to the celebration of lights the Hindus enjoy called: Diwali. I also know more about the Jewish traditions and the baby Buddha's birthday. We have Kwaanza, and solstice and Ramadan, as well as pilgrimages to Mecca and native Amerian sweat lodges. The United States now looks at the day of the Dead and Cinco de Mayo as holidays, but none of them, not one of them, are federal holidays. OnlyChristian holidays are deemed worhty enough to "celebrate" federally. Why?
Just because we have always done things this way, does not mean it is set in stone. We also are facing being politically correct in including others celebrations in publis schools, or making them generic, and Christians are upset about that. Using the word "under God" is bothersome to atheists who have no core God belief. Buddhists have no God concept either, although many of them believe in a higher power.
So, why assume that Christianity is the only religion or belief in America anymore. It isn't. And although I am not fond of Mitt Romney, why in hell is his being a Mormon even an issue. I thought we had surpassed that bias as well. And even though Obama is not a Muslim, what if he was? So WHAT! As far as I can remember, we are a "free country". the founding fathers that everyone is so quick to bring up, were diests. Look that up in the dictionary.
Perhaps the reason many are so ill informed is that they choose not to learn anything new and remain in the dark about things, making sure their beliefs are not eroded, as though it would mean their lives would have no meaning at all. Oh wait, that is the absurdist. We have lots of people with absurd ideas, but none of them would claim to believe live has no inherent meaning and make changes to reflect the times.
Let's open our minds a bit. We are all works in progress. Don't live and die ignorant.