"So Jesus said to them, 'Truly, truly, I say to you, unless you eat the flesh of the Son of Man and drink His blood, you have no life in yourselves. He who eats My flesh and drinks My blood has eternal life, and I will raise him up on the last day. For My flesh is true food, and My blood is true drink. He who eats My flesh and drinks My blood abides in Me, and I in him. As the living Father sent Me, and I live because of the Father, so he who eats Me, he also will live because of Me.'" (John 6:53-57)
What is eternal life? It is Christ Himself. In this classic passage from Scripture the Lord Jesus is again showing us that we have union with Him as He had union with the Father. In this union with His Father He lived. In this union with the Lord Jesus we live. Not merely a living forever but life where there was death before.
What does eating the flesh of the Son of Man and drinking His blood mean except union with Him? What we eat and drink becomes part of us. Physically when we do so the food and the liquid get absorbed into our body and become the very bones, sinews, and blood that enable us to function. What was once outward becomes what we actually are physically by our ingestion of it. Not merely symbols, but in the true spiritual sense the same happens to us as persons. In fact, one might almost say that the physical is symbolic of the spiritual ("For My flesh is true food, and My blood is true drink", emphasis added).
Again, the Lord Jesus points out that there is no independent life. Unless we do this we "have no life in [our]selves" (v. 53), i.e., there is no possibility of living apart from our union with Him. We have (not are "given") eternal life because we abide in Him and He in us. He is the life. When asked how we know the way, Jesus replied, "I am the way, and the truth, and the life; no one comes to the Father but through Me." (John 14:6, emphasis added). So He Himself is the life. Again, when asked to show them the Father, the Lord Jesus points to Himself not to something outward. Do we get it? His union with the Father is the same union we have with Him. His relationship with the Father is the same relationship that we have with Him. And the result is life--by His indwelling presence.