John 6:60-71 (NKJV) A Falling Away

60  Therefore many of His disciples, when they heard this, said, "This is a hard saying; who can understand it?" 61  When Jesus knew in Himself that His disciples complained about this, He said to them, "Does this offend you? 62  What then if you should see the Son of Man ascend where He was before? 63  It is the Spirit who gives life; the flesh profits nothing. The words that I speak to you are spirit, and they are life. 64  But there are some of you who do not believe." For Jesus knew from the beginning who they were who did not believe, and who would betray Him. 65  And He said, "Therefore I have said to you that no one can come to Me unless it has been granted to him by My Father." 66  From that time many of His disciples went back and walked with Him no more. 67  Then Jesus said to the twelve, "Do you also want to go away?" 68  But Simon Peter answered Him, "Lord, to whom shall we go? You have the words of eternal life. 69  Also we have come to believe and know that You are the Christ, the Son of the living God." 70  Jesus answered them, "Did I not choose you, the twelve, and one of you is a devil?" 71  He spoke of Judas Iscariot, the son of Simon, for it was he who would betray Him, being one of the twelve. ​

Questions to Consider: 

1. Have you ever known someone who renounced their faith in Christ?  (What are some of the common reasons given?)
2. How should the church respond to people who wander away from the truth?
3. ​At what point do we give up pursuing people who leave our fellowship? ​

There is a theological debate of whether or not apostasy is possible.  The question generally comes down to this: "Can a saved person lose their salvation?"  It is the wrong question to ask.  Since the goats are not separated from the sheep until the day of judgment, we don't actually know who has their name written in the Lamb's Book of Life.
Judas is a prime example of apostasy.  He was one of the 12 disciples and he betrayed Jesus.  Jesus called Judas "a devil."  By definition, apostasy is the abandonment or renunciation of a religious belief.  So, Judas abandoned his position as one of the 12 disciples and renounced Jesus.
Jesus' words concerning His atoning work offended many of those that were following Him.  Even the disciples said, "This is a hard saying; who can understand it?"  v.66 Many of Jesus disciples stopped following Him.  This is an expanded view of who were considered "disciples" of Jesus.  The twelve did not leave Jesus, but many of "disciples" walked away.
Jesus asked the 12 disciples. v.67 "Do you also want to go away?"  Peter immediately responds by sharing what He believed concerning Jesus.  vs.68,69 "To whom shall we go; We have come to believe and know that You are the Christ."
The contrast between Peter and Judas is striking.  They are both of the twelve.  They are both observing and hearing Jesus.  One has come to a place of belief and the other is on the road to betrayal.