A definition of monism is
a theory or doctrine that denies the existence of a distinction or duality in... God and the world.
In Islam, shirk is defined as
idolatry or polytheism, which means deification, or worship of deity, gods, or anything other than Allah.
It seems to be the case that monism is a form of shirk because monism asserts that the world (including its inhabitants) and Allah are a part of the same entity. Indeed, the Qur'an repeatedly makes assertions like in An-Naml (27:63)
Is there any god with Allah? Exalted is Allah above all that they associate as partners to Him.
The only possible argument that I can find in favor of monism in the Qur'an is Sad (38:72) where it says
So, when I have fashioned [Adam] and breathed into him from my soul then fall down to him prostrate.
This phrase "my soul" specifically uses the word "Ruhi" in Arabic, for which I have seen several translations, including spirit, soul and even Gabriel (the last one is unlikely here of course). I don't know the meaning of the word and I doubt anyone else does either, as it it said in Al-Isra (17:85) that
And they ask you about the Ruhi. Say: the Ruhu is of the Command of my Lord [meaninig the knowledge of which is only with my Lord] and you have not been given of knowledge but a little.
It is this question of "human divinity" that I have been pondering, especially because it seems to be a rising belief among "spiritual" non-Muslims (though this is just a personal impression). I am fairly certain that it is not an acceptable belief in Islam, but just to be sure, can someone let me know the correct interpretation of Sad (38:72) as quoted, and what Islam thinks of monism in general?