A very important verse in the New Testament is 1 Thessalonians 5:23, "And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ." Man is of three parts: the spirit, the soul, and the body.
It is easy to confuse the spirit with the soul. Some people have thought that the spirit and the soul are synonymous terms. But the Spirit of God states clearly in His Word that the spirit and the soul are two different entities and that there are three parts to our human being. These are joined by two conjunctions: "spirit and soul and body." It is also this way in the Greek text. The grammatical construction clearly shows that the spirit differs from the soul just as the soul differs from the body. The soul is not the body; neither is the spirit the soul. These are three distinct parts of one human being.
The order used by the Holy Spirit in this verse is very important. The first part mentioned is the spirit, then the soul, then the body. Outwardly we have a body, and inwardly we have the spirit. Between these two, as a medium, is the soul. From the inside to the outside are the spirit, the soul, and the body. From the outside to the inside are the body, the soul, and the spirit.
Another verse which shows these three parts of our being and the distinction between them is Hebrews 4:12, "For the word of God is quick, and powerful, and sharper than any two-edged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow." The soul and spirit are not one entity, since this verse indicates that they can be divided asunder. The soul is the soul and the spirit is the spirit, and these two can be separated just as the marrow can be separated from the joints. The marrow is within the joints; yet the marrow is not the joints, neither are the joints the marrow. They pertain to the physical body and are mentioned with the spirit and the soul. So in this verse we have again these three parts—the spirit, the soul, and the body.
In Luke 1:46-47, we can also see the difference between the spirit and the soul. Mary said, "My soul doth magnify the Lord, and my spirit hath rejoiced in God." Firstly her "spirit hath rejoiced in God," then her "soul doth magnify the Lord." These are two things done by her two different organs—her spirit and her soul.
Philippians 1:27 further reveals to us that the spirit and the soul are not one entity, but two. It says that in striving for the gospel we must "stand fast in one spirit, with one soul" (ASV). It is possible for us to be "in one spirit" (not the Holy Spirit, but our human spirit), but not "with one soul." These are two different matters related to our two different parts—the spirit and the soul.
So, according to the Scripture man is a tripartite being, composed mainly of the spirit, the soul, and the body. This is very basic for our partaking of the Triune God.