The Bible uses many terms to describe a human being. The most common are body, mind, spirit, soul, and heart. Although all of these at times refer to the whole human being, each of them commonly seems to emphasize different elements of being a human being.
The body is the material, physical, external part of being human. It is our physical flesh. It is a-moral in that it is neither inherently good nor evil. It is temporary as it returns to dust when we die (Ps 104.29; Eccl 3:20). However, it is an essential part of being human, and every person will be given a resurrected eternal body after death in which he/she will experience eternity (John 5:28-29; 1 Cor 15:52-53; Rev 20:12).
The mind refers to man’s thinking ability. It is where we invent ideas (Neh 6:8), plan the future (Pro 19:21), remember the past (Is 46:8), are convinced of truth (Rom 14:5), persuaded to understand (1 Kings 3:9; Luk 24:45), able to discern between good and evil (Rom 12:2) and wisdom and folly (2 Chron 9:23; Rev 17:9). The mind can be either, unfruitful, evil, debased, corrupt, and defiled (Rom 1:28; 1 Cor 14:14) or renewed and pure (Eph 4:23).
The term spirit often emphasized the part of man that is related to God. It is truly the immaterial part of man. The state of our spirit determines our eternal destiny (Matt 5:3), leaves when we die (Matt 27:50; Acts 7:59; James 2:26) and defines our relationship with God (Rom. 1:9, 8:16).
The soul of man emphasized the living aspect of our existence. It appears that the soul is the basis for everything immaterial including our personality, aptitude, emotions. It is immaterial and eternal and returns to God when it leaves the physical body (Rev. 20:4).
It seems that Scripture uses spirit and soul as synonyms (Luke 1:46–47) and both seem to include one’s intellect (Acts 14:2 vs. Gen 41:8; and Phil 1:27) and emotions (1 Sam 1:15).
Lastly, the heart of man seems to encompass everything immaterial about the human constitution. Your heart is your whole person—everything you are, think and do (Prov 4:23). It is at the core of human living, is inherently evil (Jer 17:9) and needs to be renewed to be acceptable to God (Rom 6:17)
It seems therefore that the human body is one distinct part of man—physical and material. All the other terms seem to be related in as much as they all emphasize different elements of the immaterial part of being a human being. The most all-encompassing of all the other terms is the word heart. Man is made up of two parts – material (the body) and immaterial (the soul/spirit/heart/mind).
The greatest commandment of all is to love the Lord your God. This commandment always includes a variety of these words that emphasise different parts of who we are (Dt 6:5; Dt 10:12; Dt 11:13; Dt 13:3; Dt 30:6; Josh 22:5; Mat 22:37; Mk 12:30; Lk 10:27). Those marked in bold include not only the immaterial part of us, but also the physical strength of our bodies. In other words, the greatest act of obedience is to love God with all of you.