Here I am playing Christmas songs for my two little sisters. My brother was off to the left, but I cropped him out keeping to my promise to not show living people without their permission. I played out of the Fireside Book of American Folksongs, a treasury of tunes including a handful for Christmas. We seem to be singing We Three Kings judging from the illustration.
Despite the totally non-religious household in which I was raised I learned numerous Christmas songs. My grade school music classes taught most of them, culminating with an annual Christmas pageant and songfest. No one in my 1950’s era questioned the overtly Christian atmosphere in the events. It was Christmas vacation and Christmas concert and Christmas play each year. I was pretty oblivious that there were any Jewish people in my neighborhood. When I grew older I learned that was probably a result of housing covenants preventing them. The first Jewish boy arrived in my class in sixth grade, but nothing changed around Christmas.
Now that I attend church regularly I can belt out Christmas carols without ever looking at the song sheets. It is ironic that my ability comes from secular settings, but that is how pervasive Christian culture was when I was a kid in Oregon.