A person is considered "whole" when his or her body, mind and spirit are in the condition God intended them to be: perfectly balanced and in agreement or at peace with each other; when there is no imbalance of any kind between these three parts. In medical terms, this is called, homeostasis. According to the dictionary, homeostasis is:
(1) The tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of the outside changing conditions.
(2) The ability of the body or a cell to seek and maintain a condition of equilibrium or stability within its internal environment when dealing with external changes.
None of us have achieved absolute perfect homeostasis on our own. We are all born into a sinful world with a sinful nature, therefore, we are all “broken” people; we are all off balance! So, how can we develop a foundation or inner core that is healthy and well balanced?
The first part of this answer is that we must experience a spiritual birth (see John 3:3-6). This occurs when we seek forgiveness for our sins through the finished work and sacrifice of Jesus Christ on the cross. At that moment, God sends Holy Spirit to live within us and we are now “born again.” God designed His perfect Holy Spirit to direct, rule, and control the rest (mind, emotions, and body) of us- in a good way.
If just one of the three parts of us is either over or under active, our whole life is off balance. In those cases, there is no homeostasis and there is a certain degree of illness.
In Luke 6:49, Jesus said,
“But the one who hears my words and does not put them into practice is like a man who built a house on the ground
without a foundation."
For no one can lay any foundation other than the one already laid, which is Jesus Christ.
1 Corinthians 3:11
When your spiritual foundation is broken, off balance, or even non-existent (as in a person who is spiritually “dead” or unregenerate, not born again) it automatically affects the other parts negatively. Your life becomes broken or off balance. Just like a house, your life will eventually collapse.
Why does this happen? Because we are created as whole human beings, every part of us is connected to the rest of us. There is no such thing as independent parts of our being. One part of us does not exist in isolation from the rest of our person.
For example, a dead or perverted spirit will leave our mind open to distorted thoughts and emotions. A sick mind and toxic emotions will then affect the body negatively. A physical body that is diseased will continue to put more limits on what a person's spirit and mind is fully capable of doing. When one part is affected, the other parts are also affected.
A description of a whole body that needs every part to function properly was used by the apostle Paul to describe the body of Christ in a healthy state:
12 For as the body is one and has many members, but all the members of that one body, being many, are one body, so also is Christ…14 For in fact the body [of believers] is not one member but many.
15 If the foot should say, "Because I am not a hand, I am not of the body," is it therefore not of the body? 16 And if the ear should say, "Because I am not an eye, I am not of the body," is it therefore not of the body? 17 If the whole body were an eye, where would be the hearing? If the whole were hearing, where would be the smelling?
18 But now God has set the members, each one of them, in the body just as He pleased. 19 And if they were all one member, where would the body be? 20 But now indeed there are many members, yet one body. 21 And the eye cannot say to the hand, "I have no need of you"; nor again the head to the feet, "I have no need of you." 22 No, much rather, those members of the body which seem to be weaker are necessary,..
1 Corinthians 12:12-22
The Scripture below describes what happens when one part is dysfunctional:
24 …. But God composed the body, having given greater honor to that part which lacks it, 25 that there should be no schism [division or separation] in the body, but that the members should have the same care for one another. 26 And if one member [one part of the body] suffers, all the members [parts of the body] suffer with it; or if one member is honored, all the members rejoice with it.
1 Corinthians 12:24-26
9
When one part of us (the church) does not function properly, the suffering is transferred in one way or another to the rest of the church body. The same thing is true of individuals. So it is imperative that we have a healthy spirit to rule or “officiate” over our mind and body.
The chain reaction goes something like this: Your spirit directs or rules your mind, your mind directs your mouth to speak what it thinks, and your body follows what your mouth says. All of that originated from your spirit and the sum total of whatever it produces is the "real you!"