In the evening just before His betrayal, capture, torture, and trial, Christ turned to Simon with these final words, encouraging him to remain strong. Of course, Peter boldly proclaimed that he would never deny Christ, but Christ knew better (vv. 33-34).
Actually, our text is quite forceful. Christ claimed that Satan has "begged earnestly" (literal translation of "desired"), not just for Peter, but for all the disciples, as seen in the plural pronoun "you," to "sift you as wheat." 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.
Christ turned specifically to Peter as the generally recognized spokesman for the disciples, and even though He knew Peter would fall, Christ informed him that he had been prayed for, that his "faith fail not." Indeed, Peter did turn around, once he saw the risen Lord, and became a leader in the fledgling church in Jerusalem, as well as a missionary. Through the witness of Peter and those he strengthened, the gospel has come to us.
Satan's desire to sift those who would spread the gospel and lead others has not abated. He knows the destruction it causes in the lives of those influenced by the one who falls. The "ripple effect" may last for years, and many weaker brothers and sisters may never recover. But take heart! The One who prayed for Peter "ever liveth to make intercession for |us|" (Hebrews 7:25; see also John 17:6-26). Just as God answered Christ's intercessory prayer for Peter, so He will answer Christ's intercessory prayer for us. JDM