This is the best explanation of the duality of man I have found. in the second part it assumes that the soul and spirit are the same entity.
quoted from http://www.ligonier.org/learn/devotionals/duality-man/
The Duality of Man
“And many of those who sleep in the dust of the earth shall awake,
some to everlasting life, and some to shame and everlasting contempt”
When theologians explore what it means to be in the image of God after
the fall, typically there is a distinction made between the imago Dei
in the narrow sense and the imago Dei in the wider sense. In the wider
sense, we can say that after the fall we are still in the image of God
because we still retain our humanity. Although sin has corrupted all
of our physical, mental, and spiritual faculties, we still make use of
them. Because we can still think, formulate plans, and the like, we
retain the image of the Lord in the wider sense. However, in Adam we
have lost the image of God in its narrower aspect. The imago Dei in
this sense is conformitas — the ability to obey God. After the fall,
man, of his own volition, can no longer conform to the Lord’s will.
Christianity confesses that God is Spirit and does not possess a physical body (John 4:24). The Lord’s moral attributes, such as faithfulness and intelligence, are not in any way dependent on physical corporeality, even though they were fully manifested in the life of Jesus. Similarly, these faculties remain present in us apart from the body. For example, we are still moral beings even if we happen to lose an arm and our bodies become incomplete.
All of this is not to say that for human beings, the body is not essential to being made in the image of God. It is the unified body and soul that is made in His image (Gen. 1:26–27). Furthermore, if we hope to be righteous we must obey our Creator with our physical flesh. Though we can distinguish between body and soul, we cannot separate them. What we do to one affects the other. The false teachers John confronted in his first epistle may have believed what they did to the body was of no consequence as long as the soul was in order, but the Bible knows of no such view.
We are the image of God physically, not in the sense that God has a human body but in the sense that we can use our bodies as instruments of holiness. We must be careful not to think the body is inherently evil. It too is “good” (Gen. 1:31), and though presently marred by sin, it will be redeemed at the resurrection (Dan. 12:2).
The Bible teaches duality — man is composed of body and soul that exist together harmoniously. This is different from dualism — body and soul are opposed to one another. We must be careful to take care of our bodies by eating well, exercising, and such things, because how we care for ourselves reflects what we think about God’s image. Consider how you care for yourself and what you must do to be healthy and glorify God with your lifestyle.