Is our humanity made up of three parts meaning trichotomy (body, soul and spirit) or two parts, meaning dichotomy (body and soul/spirit). From a theological and philosophical perspective, dichotomy makes the most sense. Trichotomy splits are humanity in ways that reek of Gnosticism and challenge the process of regeneration/sanctification. If our immaterial components are comprised of soul and spirit, which part is linked to our personhood (including will, intellect and emotions) and how does regeneration affect that in ways that aren’t ontologically schizophrenic?
Those defending trichotomy quickly cite certain proof-texts, like 1 Thess. 5:23 as proof that we are made up of three parts. A friend passed on this article recently and highlighted this quote that I thought really addressed why this is not good proof;
The trichotomist must admit, along with the dichotomist and in agreement with Berkouwer, that there is a certain ‘imprecision’ at times in the Bible’s use of the relevant terminology. One has only to consider the several New Testament quotations of Deuteronomy 6:5, for example, to see this. Where Luke 10:27 reads that we should love God with all our heart (kardia) and soul (psychē) and strength (ischys) and mind (dianoia), Matthew 22:37 reads that we should love God with all our heart and soul and mind, omitting strength, while Mark reports in 12:30 that we should love God with all our heart and soul and mind and strength (reversing the order of the last two Lukan words), and in 12:33 that we should love God with all our heart and understanding (syneseōs) and strength, using another word for ‘mind’ and omitting ‘soul’ altogether. In all, five different words are employed without even mentioning the body. Surely, no one would insist, on the basis of these series of words connected by ‘and,’ that each of these words refers to an immaterial, ontologically distinct entity, and that therefore Luke was a quintchotomist, Matthew was a quadchotomist, and Mark was a sexchotomist. With Berkouwer we must all admit that these parallel admonitions are simply saying that we are to love God with our entire or total being.
So much for using the actual words to prove the case. And to say that our total being is split in two, is ontologically and theologically challenged. Thanks Elizabeth for passing this on.
You can read the entire article here. Wayne Grudem also provides good food for thought on the subject in his Sytematic Theology (pp 472-482).
TheoThoughts 
From here: http://craigbenno1.wordpress.com/2013/08/16/what-is-the-soul/
“Craig Benno says: The following is the topic of discussion I started on my face book page, which has already started some interesting dialogue. So I thought I would start the ball rolling here and ask….What is the soul?
Do humans have a soul, or is the soul part of mythical lore? What about animals, do they have a soul? If we have a soul, where does it come from. What does it do? If we have a soul, is it ours to keep; or like what is seen in horror movies, can we or someone else sell it?
well, for those who still refuse to exalt the wisdom of men over the revelation of God, the book of beginnings tells us the origin of man and his “soul”. In Genesis 1″27 we are told simply:
So God created man in his own image,
in the image of God he created him;
male and female he created them.
A quick aside here is that God says He created both male and female in His image. This is further declared in ch.5 v.2 where we are told that He called THEIR name Adam, which some fine modern translations render as “man, mankind” etc., but the Hebrew is “Adam” which does mean those things and is also the first man’s name. The point is they are ontologically and qualitatively equal.
Then in the 2nd chapter we are given more detail and are told:
the Lord God formed the man of dust from the ground and breathed into his nostrils the breath of life, and the man became a living creature.
There is a great mystery here. The uniform testimony of the rest of scripture is that God is a unique eternal and infinite being of which there is only one and who exists in entire ontological distinction from all that He has made. Therefore, whatever it means that God “breathed into his nostrils the breath of life, it cannot mean that He extended or divided Himself into man so that man is somehow a part of God.
On the other hand, man is the only of God’s creatures that is said to bear the image and likeness of God and also the only of His creatures reported to have been brought to life by the special act of receiving his breath of life directly from God Himself. Hence man is “close” to God by God’s own act of creation in ways that no other being in the universe ever could be.
We also see here that the physical body of man is formed of the elements of his physical environment and that it cannot “live” without the animating presence of the soul. I am a dichotomist. I believe that man is comprised of a material and an immaterial component that together complete him. (different, but related topic) As we are taught other places in scripture though, the soul CAN and does survive without the body, but the very fact of the resurrection shows that man is by God’s design not all that he was created to be without a physical body.
Man, this can get long, but I only have a little while here. There are several words in each of the testaments and their respective languages that indicate, and describe man’s immaterial nature. Ruach, nephesh, leb and neshama for example in the old testament and pneuma, psuche, phronema and cardia for instance in the new. The soundest case can be made in my view that these various words for “spirit, soul, heart, mind” etc, while not strictly synonymous, are in fact telling us about the same single entity. (yes, I’ve heard EVERY trichotomous argument, but still disagree) That is, the invisible, metaphysical life essence of man in it’s various aspects and functions as brought forth from nothing by a mind numbingly powerful act of almighty God. Only God can get something from nothing.
Of the highest significance here as well is a quick rundown of what it means that man is created in the image and likeness of God. The short answer is that God Has designed man with the capacities to participate in some of His own attributes. Theologians refer to these as “communicable” attributes. Those qualities of God which He is able to share with His creatures. Some of God’s attributes CANNOT be shared. Infinity, beginning-less eternity, omnipresence, omnipotence and others.
Man can however display some of God’s nature on a finite created scale. High powers of reason, accountable moral agency, (though God is accountable only to Himself), creativity, precise spoken communication AND dominion over his environment (though God has no environment in the same way we do) are some of what it means that we bear the image and likeness of God.
As another aside, these truths make the viewing of one or more of the anthropological progressions, that is to say, “races” or “ethnicities” of men, as innately SUPerior or INFerior to any or all of the rest truly sinful. ALL men descend from the first man Adam and are therefore equally “man” in the sight of God who Himself has made it so. ALL Christians are also born again into the last Adam, Jesus Christ and as such are brethren in both covenants by temporal blood and eternal Spirit. The closest relation possible. What is unthinkably abhorrent to the Lord is alleged Christians who would idolatrously elevate the one aspect of man’s being that has nothing to do with the image of God over all the rest and define themselves by the color of their skin. There is a long history of this in the church and we need to knock it off forthwith. It doesn’t matter who does it, it’s wrong and it grieves the heart of God who created ALL men (and women) in His own image and likeness and sent His Son to die for ALL KINDS of them. (most times when we see inclusive statements about Christ dying for “all” or “the word”, that’s what it means, but that’s REALLY another whole topic.)
In Genesis 1:20 and 2:7 man and animals are both described as “living soul”, “living being, “living creature” with a very similar Hebrew construction for each. Whatever it exactly means, we can reliably surmise that animals do have souls though not bearing the image and likeness of God and not being eternal. They cease to exist when dead, while man persists after physical death in anticipation of the resurrection when he will be united to a new body either prepared for glory or fitted to everlasting perdition depending upon which Adam, and hence which covenant they died in. The first or the last.
There is very much more detail in these topics, but that’s all I have time for now.