From the Bible and from human reason we know that the human being consists of two distinct types of existence in the spiritual and in the physical in the body and in the spirit. Even atheists that I interact with in my missionary work will talk to me about their belief in the soul of the body. From the authority of the Bible we must note that the body should not be thought of as spiritual, and that the soul of the human should not be thought of as physical. The human soul is as important to our survival as is the physical body. We would have a problem on our hands if our soul left our body, or at least our neighbors would have a problem on their hands if our souls left our bodies. There is a fundamental understanding that we have within the scientific world that when our souls leave our bodies that there is nothing that can be done we are dead forever. There is something fundamental about death which because it is irreversible there is no way that the atheistic explanation for the origin of life could ever be true because if atheism were true it would be infinitely easier to give life to a completely dead organism that for life to magically spring forth from a rock. But there is a basic reality about the soul that defies the atheistic view of the world forever.
Within the human experience there is a great deal of dependence that the soul has on the body. Scriptures reveal that in the resurrection we will have bodies forever. And in the here and now we can see that the physical chemical state of our bodies helps to determine the moods that we are in and that there is an intimate relation between the physical and its impact on the state of our mind.
Moreover, there have been some who have advanced a theory about the nature of man’s reality to make a distinction not just between the physical and the spiritual, but to also make a distinction within the spiritual to distinguish between the spirit and the soul. Hence in this theory of Trichotomy there is a view which turns each and every human into a sort of trinity of person, spirit, and soul. This, as powerful of a Christian apologetic polemic as it may be, is an unnecessary theory. Ockham’s Razor would have us eliminate Trichotomy from consideration on the basis that within the Bible the words spirit and soul are used interchangeably so that we should not think that it would be necessary to force Trichotomy as a theory. But the basic premise of Trichotomy is that there are two different spiritual natures to man the soul and the spirit which could be thought of as being a distinction between the baser instincts of our nature and the basic substance that makes us who we are as individuals. Whether or not the theory of Trichotomy is true there is no basis for the theory within the Bible and is really relegated to philosophical presumption rather than anything that should be dogmatically held to or denied by the Christian.
It is worth mentioning that when it comes to humanity, that we need to think of ourselves as real. When God made the world, He really made the world. We are not merely part of a Matrix like universe as in the Hollywood film we were merely think we exist. We really exist and there really is a distinction that we can feel and which is true between the physical and spiritual realms of our existence.