Hinduism actually is monotheistic. Some Hindus are ignorant of their own scriptures.
There are many “devas” - subgods, really heads of various elements or departments if you will, in the created universe. But they honor and worship the Supreme Ishwara, or Supreme Lord, aka God.
Some ignorant Hindus think the devas are equal to the Supreme Lord, but if you talk to them politely, you might be surprised what they understand.
I'm beginning to think that most Christians also fall into this category!