We are created in God's image. God is tripartite so we are tripartite (red emphasis mine):
1Th 5:23 And the very God of peace sanctify you wholly; and I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ.
They are not the same and the scripture differentiates between them:
Heb 4:12 For the word of God is quick, and powerful, and sharper than any twoedged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart.
Your spirit is that reacted inner man that we receive when we are born again- this is the new life we receive from God. This new man is created perfect and is Christlike in every way:
Eph 4:23 And be renewed in the spirit of your mind;
Eph 4:24 And that ye put on the new man, which after God is created in righteousness and true holiness.
Your soul is your mind, will, intellect, emotions , etc- these make up your thought life. This is the area you are called to die to self in and be renewed or made new in your thinking as the Holy Spirit imparts revelation from the Word to your spirit.
We receive a new spirit when we are born again.
We receive a new body at the resurrection.
This soul is the part of you that He saves- He is the Savior of your soul.
Remember Jesus was crucified at Golgotha (the place of the skull) signifying that we must die to all our old ways of thinking and begin to think like our God with absolute faith in Him and His Word and no faith in what we see, touch, taste ,etc. There is no limit to what He can do in and through us as we simply choose to believe Him.