The passage in question is in John 6. Here is a key passage in this chapter:
John 6:53 Then Jesus said unto them, Verily, verily, I say unto you, Except ye eat the flesh of the Son of man, and drink his blood, ye have no life in you.
54 Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day.
55 For my flesh is meat indeed, and my blood is drink indeed.
56 He that eateth my flesh, and drinketh my blood, dwelleth in me, and I in him.
First, consider what this does not mean.
- It is not a command for the Jews to kill Jesus so they can, as cannibals, eat His flesh and drink His blood.
- Neither does it refer to the Lord's Supper--called by Roman Catholics and some Protestants the eucharist.
Now, let's look at the reasons it does not refer to the taking of the bread and fruit of the vine in the Lord's Supper.
To eat the flesh of Christ and to drink His blood in a literal way would make those who did it cannibals. This would be wicked.
- The drinking of blood is forbidden throughout the Bible. See Genesis 9:4; Leviticus 7:26; Leviticus 17:10-14; Acts 15:28-29. As seen in the Acts passage, even the Gentile Christians after the resurrection of Christ were to abstain from eating blood. If Christ was asking believers to eat His flesh and blood, He would be going against the clear teaching of scripture in numerous places.
- In the passage in John 6, Christ clearly told them that He was speaking in a spiritual and not a literal sense. Verse 63 states, "It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life." Here, He tells them that the flesh profits nothing and that He is referring to the spirit and not to the flesh.
What the passage is saying is that we must spiritually partake of the flesh and blood of Christ in order to have eternal life. In Hebrews 3:14, believers are "made partakers of Christ." In Ephesians 3:6, we are "partakers of his promise in Christ by the gospel." To partake is to take of something as in eating. Here, we partake of the promise in Christ by means of the gospel. The gospel is the good news of the death, burial, and resurrection of Christ for the sake of sinners in order to provide them the offer of salvation. We partake of Christ by trusting in Him. Consider these parallel passages in John 6: John 6:47 Verily, verily, I say unto you, He that believeth on me hath everlasting life. John 6:54 Whoso eateth my flesh, and drinketh my blood, hath eternal life; and I will raise him up at the last day. These verses are close to one another. The first states that everlasting life is obtained by believing in Jesus. The second states that eternal life (or everlasting life) is obtained by eating the flesh of Christ and drinking His blood. Therefore, to eat His flesh and to drink His blood means to believe on Him. Salvation involves us being uniquely identified with Christ in both His death and His resurrection. It is no more difficult to think of our selves as eating and drinking the flesh and blood of Christ than it is to think of ourselves as being "baptized into his death" (Romans 6:3), "buried with him" (Romans 6:4), and "in the likeness of his resurrection" (Romans 6:5). In reality, we are saved by eating of His holy life and drinking His incorruptible blood (1 Peter 1:18-19). But this is a spiritual truth and is not something that we must try to do physically. The real question is whether or not you have truly believed in the Lord Jesus Christ as your Saviour.