Are we two parts, body and soul, or are we three parts, body, soul and spirit?
All human beings are made of two parts, body and spirit. In scripture, the words for "spirit" and "soul" are used interchangeably as synonyms, as Dr. Arnold Fructhenbaum explains:"...the terms “soul” and “spirit” are used interchangeably and not seen in Scripture as being two totally distinct entities. That these are used interchangeably is seen in three ways. First, the same functions are ascribed to both the soul and the spirit. For example, they both get depressed (Gen. 41:8; Ps. 42:6); troubled (Jn. 12:27;13:21); both are connected with the giving up of life (Mat. 20:28; 27:50); both are seen as being in Heaven (Heb. 12:23; Rev. 6:9); both can glorify God (Lk. 1:46 47); and both were involved in the sacrifice of the Messiah (Jn. 10:15; 19:30). A second way of showing that soul and spirit are used interchangeably is that death is the giving up of either the soul or the spirit. Whether a person gives up his soul (Gen. 35:18; 1Kg. 17:21; Acts 15:26), or gives up the spirit (Ps. 31:5; Lk. 23:46; Acts 7:59), it is viewed as physical death. A third way to see that the soul and spirit are used interchangeably is that the dead are referred to by both names. Sometimes the dead are referred to as souls (Rev. 6:9; 20:4), and sometimes as spirits (Heb. 12:23; I Pet. 3:19)."
So men do not possess both a soul and a spirit. These are one and the same. Human beings possess a physical body (or flesh) made from the ground, and a spirit God "breathed" into the first man, as Genesis explains:
Gen. 2:7 Then the LORD God formed man of dust from the ground, and breathed into his nostrils the breath of life; and man became a living being.
Later, at the moment Adam sinned, the human spirit died as God promised in Genesis 2:17:
Gen. 2:17 but from the tree of the knowledge of good and evil you shall not eat, for in the day that you eat from it you will surely die.”
After the Lord had discovered the sin of Adam and Woman, He declared a curse on the ground, leading all things that come from the ground to die physically:
Gen. 3:17 Then to Adam He said, “Because you have listened to the voice of your wife, and have eaten from the tree about which I commanded you, saying, ‘You shall not eat from it’;
Cursed is the ground because of you;
In toil you will eat of it
All the days of your life.
Gen. 3:18 “Both thorns and thistles it shall grow for you;
And you will eat the plants of the field;
Gen. 3:19 By the sweat of your face
You will eat bread,
Till you return to the ground,
Because from it you were taken;
For you are dust,
And to dust you shall return.”
Since that time, Adam has reproduced after his kind, so all mankind has been born in his likeness, possessing both a body and a spirit in sin from birth. Therefore, all mankind possess a dead spirit and a dying body, but by faith in Christ, we are born again in the spirit and one day will receive a new eternal body. There is no third part.
Nevertheless, Christians (and even scripture) continue to use words like soul, heart, mind, will, etc. to describe various aspects of our being, but collectively, these labels merely describe one or the other part of our two-part nature. God created mankind with both a material form (i.e., flesh) and immaterial form (i.e., spirit or soul). Our material form will die and go to the grave, but our immaterial form is eternal, and at the resurrection, our spirit will be reunited with a new body. Our body and spirit work together to produce everything we experience as human beings, including experiences we call the mind, will, emotions, etc.
We use these labels to describe various experiences of our consciousness, but these experiences do not constitute distinct "parts" of our existence. If we could dissect a human being spiritually, we would not find a "mind" separate from a "will" and separate from "emotion." We would only find flesh and spirit. Our emotions, will, mind, etc. result from our flesh and spirit working together. The Bible says the interplay between our flesh and spirit produces all that we are. Please see Romans 7 to read Paul's explanation of how flesh and spirit work together in this way.
For example, in Hebrews 4:12, the writer of Hebrews says:
Heb. 4:12 For the word of God is living and active and sharper than any two-edged sword, and piercing as far as the division of soul and spirit, of both joints and marrow, and able to judge the thoughts and intentions of the heart.
In this verse, the writer uses "soul" and "spirit" as synonyms for our spirit, just as he uses "joints" and "marrow" as synonyms for flesh. The writer uses two synonyms for each part of mankind. Therefore, Hebrews is saying that the word of God separates the immaterial (soul, spirit) from the material (joints, marrow). The writer was not defining four parts to our existence.
In a second example, Paul refers in IThessalonians 5:23 to spirit, soul, and body:
1Th. 5:23 Now may the God of peace Himself sanctify you entirely; and may your spirit and soul and body be preserved complete, without blame at the coming of our Lord Jesus Christ.
Though Paul uses three terms in his list, we can find other scriptures that make even more distinctions. For example,
Luke 10:27 You shall love the Lord your God with all your heart, and with all your soul, and with all your strength, and with all your mind; and your neighbor as yourself.
Based on this single verse, are we to conclude that mankind consists of four elements: heart, soul, strength, and mind? If one applies the same logic of interpretation to Luke 10:27 as in I Thessalonians 5:23, then we would have to conclude that man has four distinct parts, not merely three. But clearly, this was not Christ's intent when He spoke those words.
Therefore, assuming each label in 1Thess 5:23 describes a separate element of our being is faulty logic and improper interpretation. In reality, writers of scripture often use synonymous terms in a list to add emphasis to their point. So when Paul said "spirit and soul" he was emphasizing the entire spirit of man. He wasn't describing two different elements of our nature, no more than Christ was describing four parts to our nature in Luke 10:27.