Ask yourself, is the functioning brain identical to the mind? If your answer is no, you are a closet dualist. You believe that brain and mind are made of different kinds of stuff. Such a stance will make it hard for you to understand the nature of consciousness. It will make the mental aspects of our lives mysterious and unknowable.
I am a working neurologist who sees brain disease causing mental dysfunction every day. Take the case of Representative Gabrielle Giffords. If she does not recover pretty much full brain function, her mental states will be altered, and she may not be able to function in Congress as she did before the bullet damaged her brain. If the bullet had done more damage than it apparently did, she might not now be fully conscious. Hopefully she will recover. There is the famous case of Phineas Gage, however, in which brain damage to the frontal lobes of the brain by a railfoad spike turned a sober, hard-working man into a lout. His mind was altered because his brain was altered. He was a different person after that spike went through his brain.
The main reason many people remain dualists, however, is because they find it impossible to believe that brain function can entirely explain consciousness. They think that after all the neurotransmitters have hit their receptors and all the neurons have fired, there is still something that has been left out of any explanation of consciousness. The thing that has been left out, they say, is the conscious feeling of what is like to be in a certain state. Furthermore, all the whirling electrons cannot explain why a certain neuronal configuration results in our seeing blue rather than red. Another objection that I have heard is, "What about my soul"? So they conclude than consciousness cannot be fully explained by brain function. But if that is true, where is consciousness and what is it?
As a neurologist, I contend that consciousness is nothing more than the ability of our brain to acquire information (which is the state of being awake) AND all the content that the information contains AND the ability to get all that information into and out of memory. The key word is "ALL". If you have all that, you are conscious of the blue sky and the red sun. Nothing more is needed to be conscious of that beautiful sky. My contention is that the brain can do all that, and, therefore, a functioning brain is identical to a conscious mind. That makes me a materialist and not a dualist. In the coming months, I want to explore these ideas. I want to hear what you think, your objections to my position and your arguments for and against these ideas.