"And the Lord said, Simon, Simon, behold, Satan hath desired to have you, that he may sift you as wheat: But I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren" (Luke 22:31-32).
Christ said these words to Simon Peter on the evening before He was betrayed, tortured and tried. It was Passover, Jesus had just instituted the Lord's Supper and had told them that one of the disciples would betray him. There had then been a dispute among them about which of them should be considered the greatest. Christ had explained the servant nature of discipleship and that those who continued with Him in trials would sit on thrones and judge Israel.
After all this Jesus predicted Peter's denial of Him. Peter being Peter, he boldly proclaimed that he would never deny Christ, asserting that he was not only ready to go to prison for Christ, but to his own death, to which Jesus said, “I tell you, Peter, the rooster shall not crow this day before you will deny three times that you know Me.”
As was the case with Job, God allowed Satan to tempt Peter. Satan knew (as he still knows) that the fall of Christian leaders causes many others to fall, and if all of the disciples could be made to abandon the faith, the gospel could not be spread.
I think it was good for Peter to have heard this from Jesus in advance.
He was devastated by his own denial of Christ, which served to teach him important lessons.
One lesson was that although he was an intimate friend and follower of Jesus he was still human and susceptible to failure. He also learned that over-confidence can result in deadly disobedience when that confidence is in our own ability, even to remain faithful.
Satan still desires to sift followers of Jesus, knowing the destruction it can cause to the believer and to those around him.
Aren't you glad for the stories of Peter that are in the Bible, and for the knowledge that the One who prayed for Peter "ever liveth to make intercession for (us)"? (Hebrews 7:25) What a great comfort it is to us to know that Christ will also intercede for us when we fail.
We all do.