In order to understand the sacrifice required of us for the building of God's habitation, we have to understand the aspects of our salvation. It has past, present and future aspects. Man is a spirit made in the image of God and he lives in a body. The soul is the result of the spirit of man coming into the body (Genesis 2: 7).
Adam and Eve were made perfect and enjoyed sweet fellowship with the Lord in the Garden of Eden. They were made to live forever, but lost the gift of immortality due to the fall. They also lost fellowship with God and were driven out of the Garden of Eden to keep them away from the tree of life, that they would not eat of it and live forever in their fallen state. From then onwards man needs to be redeemed, spirit, soul and body from death that resulted from this fall. The redemption came through the sacrifice of our Lord and saviour Jesus Christ on the cross on Golgotha.
The past aspect of our salvation
The past aspect of our salvation concerns what happened to us when we were born again. It is the first thing that happens to us in God's plan of redemption. Without this birth, that is, justification, no man shall see the kingdom of God. Jesus said to Nicodemus:
……Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God (John 3: 3).
When we received Christ, our spirit man became quickened and was brought to life. Born of the Spirit, with life from above, we became capable of communication with God from that moment. In other words, when we received Christ, we got a new spirit (our spirit man was saved). The salvation of the spirit man is through faith, not of our own works.
For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: Not of works, lest any man should boast. (Ephesians 2: 8 -9)
At this point, however, the soul and the body are not yet regenerated. The need for man to be restored both in the soul and the body brings us to the present and future aspects of our salvation.
The present aspect of our salvation
We are to renew our souls in the present. True, we've been saved, but our souls are not changed at the time we are born again. Therefore, each of us is called upon to work on the salvation of our own souls (renew our souls). Paul said to the Philippians concerning the renewal of the soul:
Wherefore, my beloved, as ye have always obeyed, not as in my presence only, but now much more in my absence, work out your own salvation with fear and trembling. (Philippians 2: 12)
Why we too must work out the salvation of our souls with fear and trembling is because it is here where a lot of people lose the battle. Many have had their spirit quickened (born again), but few are chosen because the majority of them (those who are born again) lose the battle for the salvation of their souls.
The extent to which our souls are changed depends on each of us individually. This is because the change comes by reading and meditating in the word of God. No one can read or meditate in the word of God for another; we've got to do it ourselves. God has not left us helpless or alone in this battle. He has given us power to become sons of God. This power is present in all who have been born again (John 1:12).
It is up to us to use the power given us, to deny the demands of the old nature within us, the world, and the devil, so that our souls may be saved. In other words, the salvation of our souls is about completely killing the old self we used to be and inwardly changing into the likeness of Christ. When that happens, we can say with Paul,
I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me. (Galatians 2: 20)
It is important to understand that the renewal of our souls is a must. We see in Romans chapter 8 that to be carnally minded is to be against God. It is the leading of the Spirit of God in our lives that ensures our entry in through the strait gate (Romans 8: 14).
Therefore, we are to mortify the flesh by living in the Spirit so that we may be sacrifices without blemish for the building of Zion (the Church). Our faith must persevere to the end if we are to enter into life; and the end of our faith is the salvation of our souls (I Peter 1: 9).
The future aspect of our salvation
The part of our salvation that remains to be done in the future is that of the restoration of the body to the perfect state in which God formed it when He made man. What will happen in the future is: when Christ returns, we shall receive new bodies which are immortal (I Thessalonians 4: 16-17). In a moment we shall be changed at the trump of God and get caught up in the air to meet the Lord and we shall be with Him forever. This is the point at which God's plan to restore man, spirit, soul and body, will be completed.
In summary, the sacrifice we are required to bring for God for the building of the Church is our renewed souls - it is not until we are renewed that we can yield to the will of God.