The longing is in our soul, too, because God put it there when He made us in His own image. In our fallen condition, we may not be always aware of this longing. But we can certainly feel its symptoms, which are powerful themselves. We have many legitimate desires: for food and water, for comfort and rest, for pleasure and happiness, for knowledge and growth, for approval and praise, for companionship and love, etc. We can say that God Himself put these desires in us because He made us psycho-somatic beings.
According to other religions, salvation is presented in individual terms—whether it is enlightenment or perfection. But Christianity presents salvation as communal or covenantal—that is, in our covenantal union with God. Not only that, we are saved as members of the body of Christ, in a community, not as separate individuals. You can see why. Our redemption cannot be complete without meeting this greatest and most fundamental desire of our being. It was for this that God made man in the beginning. God did not create man out of some kind of need or lack in Himself. God is self-existent and self-sufficient. God created man, not out of any need in Him, but out of His overflowing abundance. He created man because He desired other moral beings to experience His happiness and joy in communion with Him! It is through union with Christ that God grants us the full satisfaction of our deepest longing. Our salvation is not in getting every spiritual blessing from Christ; rather, each spiritual blessing is an aspect of enjoying Christ in His multi-faceted and all-sufficient love for us. God is the Fount of every blessing because He is the essence of all that is good. God is the Fount of life and He is the Life. God is the Creator of all and He is all in all. Christ is the Savior and He is the Salvation. Let us learn to be content with Christ. Let us learn to glory in Christ and boast in Him as our greatest Treasure and Friend!