Are Hindus considered Ahlul Kitab?

In order to be Ahlul-Kitab, you must believe in Monotheism, as many scholars have said, a Hindu that has read Bhagavad Gita or any Hindu book understands that Hindu is actually monotheistic, and so if Educated Hinduism is monotheistic, is it still considered shirk to be worshipping only 1 god? I understand that such god has a idol, but many Hindus agree that idle is just for them to concentrate on their worship, and does not define any true physical appearance. So if such is true, are these Hindus still considered shirk?