God made man as a tri-partite being: body, soul, and spirit. The body is the physical, material part of man. The soul is immaterial, the life-principle of personhood (mind, will, and emotion). The spirit is the other primary immaterial part of man. The spirit of man is the part that actuates the life principle itself.
The Hebrew word for spirit is ruach, which means “wind, breath, spirit”; and the Greek counterpart is pneuma. Genesis 2:7 says that God breathed into man’s nostrils the breath of life, and that is when man became a living soul (nephesh). The life-principle that activated the soul to become living was the breath of God. James 2:26 says that human physical life ends when the human spirit departs from the body (cf. Gen. 25:8; Lk. 23:46).
The spirit of man is associated with his personhood—mind (Mk. 2:8), emotion (Mk. 8:12), and will (Lk. 1:80)—and frames his outlook on specific situations and on life in general. It thus characterizes his disposition (e.g., proud, hasty, fearful, gentle, meek, or wise).
The spirit of man is the part that communes with God, even as God is a spirit (Jn. 4:24; Philip. 3:3). At death, the spirits of believers return to God (Lk. 23:46; Acts 7:59), but the spirits of lost men depart into hell (I Pet. 3:19). While we live, we are to glorify God in our body and in our spirit, which are God’s (I Cor. 6:20).