I think it is more difficult than we realize to wrap our minds (and our hearts) around monotheism. While I think that anything else is incoherent, we are pretty incoherent creatures.
Consequently, people slip into dualism a LOT, whatever we profess.
aruanan brings up theological dualism (Manichaean, good and evil) and you bring up philosophical dualism (mind-body problem, et al) - of which, there are many forms and arguments for and against.
I find myself in disagreement both with the above article and the critics of philosophical dualism on both Scriptural grounds and the grounds of mathematics and physics.
All other physical cosmologies (multi-verse, multi-world, imaginary time, ekpyrotic, etc.) fail for their inability to explain the beginning of real space and real time: in the absence of space, things cannot exist; in the absence of time, events cannot occur; both space and time are required for physical causation.
There is also the issue that since the 1960's forward, cosmic microwave background measurements agree that space/time does not pre-exist but is created as the universe expands. That is the most theological statement ever to come out of modern science, i.e. that there was a beginning of space/time - "In the beginning, God created..."
Indeed, the whole concept of linear time, which the author of the article posits as truth, is observer dependent. Or to put it another way, that we mortal observers sense time as an arrow, linear and moving in one direction does not mean ipso facto that additional dimensions of time (Wesson, Vafa) do not exist or that God is in anyway constrained by "time."
In other words, space/time is part of the Creation not a property or restriction on the Creator of it.
Finally, as a personal testimony, I have observed the separating of the spirit from the body in physical death. In both my mother and sister's passing - as they slipped into the final coma - I felt them both passing through me, comforting me, assuring me that they were very much alive and happy.
And I was with my husband scuba diving when he passed diving in the "emerald sea" as it is called off the coast of Panama City, Florida. The water is greenish there and as the diver descends it turns an ever-deepening blue. He had fallen back to 75 feet of water and as I approached him the area immediately surrounding him was bright and yellowish, as if a spotlight were shining on him. I'm certain the light was his spirit separating from his body. And I'm certain that God mercifully let me see this to comfort me as he was calling him home.
I am not alone in this testimony as many children have also spoken of such a separation of their soul and body during their near death experiences. We might expect adults to conjure stories whether intentional or not - but children having similar experiences defies such reasoning.
God's Name is I AM.