Commentaries:
Unless we eat His flesh (represented by the unleavened bread of the Passover ritual) and drink His blood (symbolized by the wine), we have no life in us and will not inherit eternal life! It is vital, therefore, for all converted Christians to observe the New Testament Passover every year.
Earl L. Henn
Holy Days: Passover
These people knew well that Leviticus 17:10-11 forbids the eating of blood. They should have understood that He was not speaking of literally drinking the blood coursing through His body. If they knew Him from His youth, as they had earlier claimed, they should have known He was the most law-abiding person they had ever witnessed. What Jesus means is: "He who accepts, appropriates and assimilates, and understands My sacrifice as the only ground of his salvation remains in Me and I in Him." This is why He adds, "He who eats My flesh and drinks My blood dwells in Me and I in Him." He is the living Word.
As physical food and drink are offered, accepted, and eaten, so also must Christ's sacrifice be offered, accepted, and eaten. As the stomach assimilates the physical, so His sacrifice is spiritually assimilated in the heart of believers. As food nourishes and sustains the physical body's life, so Christ's sacrifice nourishes and sustains spiritual life.
John W. Ritenbaugh
Eating: How Good It Is! (Part Four)
Other Forerunner Commentary entries containing John 6:54:
Genesis 3:4
John 3:1-12