The scriptural reference usually relied upon is: "May your whole spirit, soul and body be kept blameless at the coming of our Lord Jesus Christ." (I Thess 5:23)
God said it, and I believe it, and that settles it, right?
Not so fast though....as scripture needs to comment on and be compared to scripture, in order to get a balanced full orbed view. One of the first principles of biblical interpretation is that whenever possible, let the bible interpret itself--that is, look up ALL relevant passages on a subject, particularly important is letting the New Testament interpret the Old Testament before settling your opinion on something. It's not that we don't take the bible literally....but we MUST take it how it was intended, as inspired by the Holy Spirit, as a whole--for us today.
For example, Exodus 22:18 says, "Thou shalt not suffer a witch to live." So that settles it right? We need to kill witches? (Salem Mass. Puritans thought so...) NO. As the New Testament, while also condemning necromancy and witchcraft, never calls on the people of God to execute anyone--execution, and other civil penalties, were part of the law written for the ancient theocratic Kingdom of Israel--which ceased to exist centuries before Jesus walked on earth. Still, we CAN know from Ex 22:18, as well as passages such as "Let no one be found among you who ... practices divination or sorcery, interprets omens, engages in witchcraft, or casts spells, or who is a medium or spiritist or who consults the dead." (Deut 18:10) that God doesn't approve of occultism, affirmed in the NT in Galatians 5:19. 20: "The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft;"
But by letting the New Testament (NT) interpret the Old Testament (OT), we know we should not apply the civil law penalties of the theocratic government of ancient Israel today--as today the Kingdom of God is NOT a civil-political system, it is "not of this world." (Jesus to Pilot in John 18:36). And nowhere in the New Testament are Christians ever called on to use force to establish or advance God's Kingdom. Therefore, I can know for sure, it is morally wrong to kill witches today, just for dealing in the occult. It's not that I don't take the bible literally--it's that I take it as interpreted by itself--and seen through the lens, as it were, of the New Testament.
The same principle applies to New Testament teachings...they need to be compared to other New Testament teachings, (and OT teachings, if possible) in order to, as much as possible, let the Word of God interpret the Word of God....
So lets get back to the initial question: Doesn't I Thess 5:23 PROVE people have 3 parts, body, soul and spirit?
No. Not when we look at other passages relating to human nature. Here's why:
- The lists of parts varies: "Jesus replied: ' "Love the Lord your God with all your heart and with all your soul and with all your mind."'" (Matt 22:37) "Love the LORD your God with all your heart and with all your soul and with all your strength." (Deut 6:5)
- Other passages indicate two parts only: "Do not be afraid of those who kill the body but cannot kill the soul. Rather, be afraid of the One who can destroy both soul and body in hell." (Matt 10:28) "But if Christ is in you, your body is dead because of sin, yet your spirit is alive because of righteousness." (Rom 8:10) "Her aim is to be devoted to the Lord in both body and spirit." (I Cor 7:34b)
- Or maybe even 4 parts: "Love the Lord your God with all your heart and with all your soul and with all your mind and with all your strength."(Mark 12:20 and Luke10:27)
- Or possibly, 7(?!) parts: "For the word of God is living and active. Sharper than any double-edged sword, it penetrates even to dividing soul and spirit, joints and marrow; it judges the thoughts and attitudes of the heart."
So the neat and tidy system, taught in many bible schools, seminaries and pulpits, of humans having exactly 3 parts, body soul and spirit, is NOT established in scripture, and may be properly said, (as with the the 4 or 7 part examples) to be a figure of speech, listing elements of who we are as people, but not as any form of an exhaustive, scientific definition.
It's safe to say we are what we appear to be: Bodies, and (much) more than bodies, descendent from Adam, who was made in the image of God.