You are made up of atoms. That does not mean you are atoms. You have a brain. That does not mean you are your brain. Your thoughts are caused by patterns of neurons. That does not mean your thoughts are patterns of neurons. This mistake, "reductionism," or reductive thinking, reduces everything to its' component parts or causes. This mistake happens all the time, especially in the age of science. We have heard the mantra many times, usually with the pessimistic "nothing but" added on. We are nothing but apes, or brains, or emotions or whatever. But it's wrong and deceptive; it limits are thinking, reduces our consciousness, impoverishes our experience, and constricts our horizons.
Plato and Aristotle recognized that there are different meanings to the word is, am, are. For example when we say "I am atoms bouncing around in space," that's true. But it really means "I am composed of atoms bouncing around in space." See the difference? Don't confuse what you are with what you are made of.
Second, we confuse things with what causes them. For example some guy says to his wife: "My love for you is nothing more than chemical signals from my brain making me feel a certain way [or insert another scientific-sounding cause for emotions]." That's not right. Love, of course, has many fascinating causes, but love is something different and larger than what causes it. It's an experience beyond words. Faith too. Thunder is not lightening, yet lightening explains thunder.
We mistakenly reduce things into their properties too. God is love, said Paul. I agree. But that's presumably just one of God's properties, along with others. I am a father. I am smart. The philosopher Rene Descartes famously said "I think; therefore I am," by which he meant the property of thinking proves the existence of a thinking being. He was right. On the flip side, Immanuel Kant famously said that existence is not a property. He was right.
Which brings us to the is of identity. When I say "I am," it means I exist. Being, existence; that's fundamental. This is the more mysterious one. When God said "I am who I am," he meant it sorta like that; something like "I am the ground of all Being". Similarly, when we say we have a mind or soul, we mean the soul is our ground of being, our changeless self, our highest form of is. I am Matt, a unique person that exists through time, space, and maybe even beyond that.
So, in the end, I am many things and you are many things, big and small: a brain, a body, a consciousness, a personality, a mind and a soul; memories, dreams reflections. I consider the brain hugely important, most important. But before we start reducing things into their lowest parts, let's think. The problem with Reductionism is that, in its fever to explain things, it tries to explain things away; it confuses identity with causes, compositions, and properties. As Whitman said, "I contain multitudes: I am large."