While often such a turnabout in a two-year-old can be a reaction to something on the inner planes, it may simply be linked to physical pain.  For instance, a toothache.  Since he can’t express himself well, he rejects something he knows you regard as both good and important.  Later, as the pain lessens, his reaction to HU will also reduce.

But it depends upon how the parents respond when the child rejects an important value of the family, like the teachings of ECK.  He’ll remember your reaction and may use it in the future as a way to control you.  Children do that.

Be compassionate to his pain, but be firm about the goodness of ECK.