When God created man, He did something entirely different than when He created all other life.  "...the Lord God formed man...and breathed into his nostrils the breath of life; and man became a living soul." Genesis 2:7  That breath, the Spirit of God, is what made the human soul.  God didn't breathe Spiritual life into any other animal.  Only man.  And only humans have the capacity to hold His Spirit.  We have a unique place within us that God intended to be filled with Himself.

We were created specifically with the capacity to hold God within us.  That is what salvation is--God himself living inside us.  Paul explained what happens when a human receives the Spirit of God within his heart:  "For it is God which works within you both to will and to do His good pleasure." Philippians 2:13  God within us is what causes us to want to do his will.

Paul said this to the Corinthians in 5:17 "...I live, yet not I, but Christ lives within me..."  We have physical life like the animals, but we are unique because we have a greater capacity than the animals.  We have the capacity for Spiritual life.

Adam had it.  But after sin occurred, people were born empty.  Sin made us unfit to hold God's Spirit.  But God had a plan to restore us and to put his Spirit back within the human heart.  "A new heart...I will give you, and a new spirit will I put within you...I will put my spirit within you, and cause you to walk in my statutes...and do them."  Ezekiel 36:26-27  We may be incapable of being Christ-like, but God isn't.  God's plan was to reconcile man to Himself by dying for our sin.

This "Spirit within" the human body is unique.  We read in the Bible about the only other human born with (starting out with) the indwelling Spirit in 1 Corinthians 15:45  "And so it is written, the first man Adam was made a living soul; the last Adam became a life-giving Spirit."  Another version says: "The Scriptures tell us that the first man, Adam, became a living person, But the last Adam--that is Christ--is a life-giving Spirit."

Getting the Spirit of God back where God intended it to be is the entire message of the gospel.   "Christ in you, the hope of glory." Colossians 1:27