"60 When many of his disciples heard it, they said, “This is a hard saying; who can listen to it?” 61 But Jesus, knowing in himself that his disciples were grumbling about this, said to them, “Do you take offence at this? 62 Then what if you were to see the Son of Man ascending to where he was before?63 It is the Spirit who gives life; the flesh is no help at all. The words that I have spoken to you are spirit and life. 64 But there are some of you who do not believe.” (For Jesus knew from the beginning who those were who did not believe, and who it was who would betray him.) 65 And he said, “This is why I told you that no one can come to me unless it is granted him by the Father.”
66 After this many of his disciples turned back and no longer walked with him. 67 So Jesus said to the Twelve, “Do you want to go away as well?”68 Simon Peter answered him, “Lord, to whom shall we go? You have the words of eternal life, 69 and we have believed, and have come to know, that you are the Holy One of God.” 70 Jesus answered them, “Did I not choose you, the Twelve? And yet one of you is a devil.” 71 He spoke of Judas the son of Simon Iscariot, for he, one of the Twelve, was going to betray him."
John 6:60-71
The offer of the bread of life implies and involves fellowship with Christ in His death, and this means an experimental crucifixion of all that is natural and fleshly in the heart, if we would taste of the hidden manna and be satisfied. It means dying to sin daily, accepting the discipline of the cross daily in our lives, letting its heart-bruising message slay all manner of evil things in us, mortifying the deeds of the body through the Spirit. This is just another way of saying that in Christian experience we die to live. We must be brought into captivity to the obedience of Christ before we can know the freedom of the gospel. Crucifixion precedes resurrection in the experience of the believer. And this is the price many are not prepared to pay, and they therefore go hungry and their souls are poverty-stricken and lifeless. For them the message of fellowship with Christ in His cross is far too devastating and rigorous; it is a stumbling block, because the life of the flesh, with all its seductive charms, sometimes on very high, legitimate levels, is too attractive to them and means too much to them. Furthermore, it means a Christ-centred life. Jesus says, ‘I am the bread of life', therefore feed on Me alone, find all your satisfaction, fullness and blessedness in Me. At first, this sounds attractive to the natural heart, but it is really the heart of the offence, for it means a one-track life in the fullest sense of the term. Paul expressed it in the words, 'To me to live is Christ'. This is not always appreciated by Christians. So often, in the lives of believers, there are other centres to Christian life, Christian service, Christian fellowship, Christian concern. What do we live for? These things, good in themselves, are still things, and only fellowship with Him can satisfy our hearts. It is not that service or fellowship must go (how could we think so?) but that they should be displaced from the centre and given their proper place, and be rid of all that is fleshly in them. Our interests, habits, recreations, friendships - everything must come under the discipline of the cross. Only then can they be free from the danger of competing with Christ.