As a diehard communist, he would have planted in their minds at an early age that Christmas was an "evil" thing (even many mere Libs do this). He wrote poems attacking Christianity.
Barack Obama, from Dreams from My Father, Three Rivers Press, New York, Revised Edition, 2004, ISBN 1-4000-8277-3, p. 76-7:
"But by the time I met Frank [Frank Marshall Davis] he must have been pushing eighty, with a big, dewlapped face and an ill-kempt gray Afro that made him look like an old, shaggy-maned lion. He would read us his poetry whenever we stopped by his house, sharing whiskey with Gramps out of an emptied jelly jar."
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Frank Marshall Davis
From Accuracy In Media | AIM.ORG
Obama’s Red Mentor Praised Red Army
AIM Report | By Cliff Kincaid | April 30, 2008
Barack Obama’s childhood mentor, Frank Marshall Davis, a member of the Moscow-controlled Communist Party USA (CPUSA), wrote a poem dedicated to the Soviet Red Army. “Smash on, victory-eating Red Army,” he declared. He also wrote poems attacking traditional Christianity and the work of Christian missionaries.
http://www.aim.org/aim-report/obamas-red-mentor-praised-red-army/