Seeking or Settling, 5; John 6:59-71

John 6:59 tells us, "Jesus said these things in the synagogue, as he taught in Capernaum."  In verses 60-66, we have another sad section of the chapter.  It begins and ends with the expression, many of his disciples.
In the ESV, verse 60 reads, "When many of his disciples heard it, they said, 'This is a hard saying; who can listen to it?'" whereas the same verse in the NKJV states, "Therefore many of His disciples, when they heard this, said, 'This is a hard saying; who can understand it?'"
What was so hard?  What challenged these many that they left off following Jesus?  The issue was not listening or understanding but perhaps that they understood all too well, and they did not like what they heard.
"But Jesus, knowing in himself that his disciples were grumbling about this, said to them, 'Do you take offense at this?  Then what if you were to see the Son of Man ascending to where he was before?'" (v. 62)  [Grumbling: complain or protest about something in a bad tempered but typically muted way.]
Even that would not bring about faith in them; why not?  Jesus continued, "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.  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.)  And he said, "This is why I told you that no one can come to me unless it is granted him by the Father" (vv. 63-64).
It appeared that many had not had this granted to them, based on verse 66:  "After this many of his disciples turned back and no longer walked with him."
Jesus has gone from a large crowd at the beginning of John 6 to a dozen men by 6:67.  And then Jesus took the initiative and said to the Twelve, "'Do you want to go away as well?'  Simon Peter answered him, 'Lord, to whom shall we go?  You have the words of eternal life, and we have believed, and have come to know, that you are the Holy One of God.'  Jesus answered them, 'Did I not choose you, the Twelve?  And yet one of you is a devil.'  He spoke of Judas the son of Simon Iscariot, for he, one of the Twelve, was going to betray him" (vv. 67-71).
I assume that when Judas did not dissent from what Peter had said, the rest of the Twelve thought he was in agreement with them.  Jesus knew that was not the case.
What did so many leave off following?  Only the called are enabled by the Holy Spirit to persevere.  Jesus made this clear numerous times, as would others (see Philippians 1:6, 2 Thessalonians 5:23-24, for examples.)
Earlier in John 6, Jesus made the clearest statement of who and what he is:  "Jesus said to them, 'I am the bread of life; whoever comes to me shall not hunger, and whoever believes in me shall never thirst.... All that the Father gives me will come to me, and whoever comes to me I will never cast out.  For I have come down from heaven, not to do my own will but the will of him who sent me.  And this is the will of him who sent me, that I should lose nothing of all that he has given me, but raise it up on the last day.  For this is the will of my Father, that everyone who looks on the Son and believes in him should have eternal life, and I will raise him up on the last day" (vv. 36-40).
Is that so hard to understand?  No, but we always want to have some way to get credit for our salvation, which is why the question was asked, What do we do to do the works of God?  We cannot wrap our wicked minds around the fact that only the Holy can satisfy the Holy.
And none of us is holy in and of ourselves.  Only Jesus is.  But there is hope to have his holiness be considered ours and our wickedness considered his:
2 Corinthians 5:21:  "He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him."
Romans 10:9-13:  "That if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved; for with the heart a person believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation.  For the Scripture says, 'WHOEVER BELIEVES IN HIM WILL NOT BE DISAPPOINTED.'  For there is no distinction between Jew and Greek; for the same Lord is Lord of all, abounding in riches for all who call on Him; for WHOEVER WILL CALL ON THE NAME OF THE LORD WILL BE SAVED."