John 6:56, "He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him."
Many thought that Jesus was speaking of cannibalism, but He was speaking of the spiritual man. Just as the physical man receives life from the food he eats, so the spiritual man receives life as he partakes of Jesus, the life of men (Jn. 1:4; 10:10; 14:6) or the "Bread of Life." Just as the life of a root is found in the soil, or a branch in the vine, or a fish in the sea, so the believer's true life is found to be in union with Christ.
The Bible presents salvation as a life transforming experience. Change is one of the distinguishing characteristics of a true believer. Yet, failure to understand that this change takes place in the spirit first, and is then reflected in the outward thoughts and actions, proportional to the way we renew our minds, has caused much confusion. This change has to take place in our bornagain spirit. Why is that? If you were overweight before you got saved, you will be overweight after you get saved, unless you go on a weight loss program. Your body doesn't instantly change. Also, your soulish or mental realm doesn't instantly change. How you thought about things before you got saved will be how you think after you get saved, until you start renewing you mind. The only part of you that is left is your spirit. It is your spirit that is instantly changed at salvation. It is perfect (Heb. 12:23). It cannot sin (1 Jn. 3:9). Everything that is true of Jesus is true of our bornagain spirit. Your spiritual salvation is complete. At salvation, you receive the same spirit that you will have throughout all eternity. It will not have to be changed again or cleansed again. It has been sealed with the Holy Spirit (Eph. 1:13) and is therefore sanctified and perfected forever (Heb. 10:10, 14; 12:23). Jesus lives in the spirit of believers. All that He is will be available to you if you will depend on Him instead of your own abilities.