FWIW Buddhism is different from the "People of the Book" (Jews, Christians, Muslims all worship literally the same God.) Buddhism is not monotheistic.
(The resolution between these forms was given in South Park of all places: God appears on Earth and mentions in passing that He is Buddhist.)
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Uh, heh, Hinduism is also different from the "People of the Book", and from Buddhism. The Gita is, of course, Hindu, not Buddhist. (I'm not sure how I got confused in the previous portion of this comment, sorry. No offense intended!)
If one is reading Holy Bible or Koran, one needs to adhere that they are the only god.
But in nowhere in Hinduism, Buddhism, Jainism, Sikhism, ...
Or any other religions from Indian origin claim their's is the only truth.
All of them are completely fine with different view points.
For example Hinduism is too broad, it literally accepts everything.
For Ex:
There is only one God, there are many gods, there is no God.
One can be an atheist and be a good Hindu.
You need to pray to god, you shouldn't pray to god.
But there is an unification among all Indian religions. For ex: All religions go in search of God/Truth.
Any how, Bhagavadgita, should rather be looked up-on like a more of philosophical text rather than religious book.
It is the essence of MahaBharata, yet another religious text book.
Intellectually very challenging.
Even though it is a religious book for many people, it can be read as just a normal story.
It teaches one about how to live life, not by set of defined rules, but by providing a proper explanation and through understanding.
It's a book which is usually dated to 5000 years or 7000 years.
It`s a very well-balanced story, one can ignore parts which are not relevant to present society.