In this situation everything BHO stands for is inherently wrong and dangerous. Marxist-Leninist philosophy is inherently dangerous, there is nothing virtuous or good that comes from it.
I think I can explain the parents:
First, understand that in the minds of many leftists, not only is there no God, there are no transcendent realities at all. The state, or maybe society, or humanity as an abstraction, holds the same place in their world-view as God does for the theist. For the American state-worshipper, Obama is obviously as messianic figure.
The little sing-along was simply a state-worshipping analog of having children in Sunday school sing “The Old Rugged Cross” or “Jesus Love Me”.
They are doing what parents do: attempting to pass on their beliefs, attitudes and mores to their children.
Be glad that folks of their persuasion tend not to reproduce.